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ΓòÉΓòÉΓòÉ 1. OpenGL WWW Pages Intro ΓòÉΓòÉΓòÉ
OpenGL man pages
The OpenGL WWW Pages (Version 1.0)
The OpenGL man pages for OpenGL version 1.0 have been reformatted into HTML
for your reference. At this time it is not part of our Open3D product, but
merely a convenience for our customers. (And web surfers.)
These man pages represent the following versions of the OpenGL standards:
Specification Version
------------- -------
OpenGL 1.0
GLX 1.1
GLU 1.2
HTML does not have a good way to write mathematic equations. I have done my
best to represent the various formulas in the man pages into something readable
on character-based readers. I have used one ISO Latin-1 one character, the
raised dot (Γòû, hex b7), to indicate multiplication. If this is a problem for
people I can change it to `*'. Superscripts are placed on the line above and
subscripts are placed on the line below their referent. Fortunately I didn't
run across any instances of subscripts on one line followed by superscripts on
the line below.
My primary goals are
1. Make the man pages readable and correct.
2. Make sure the formulas, equations and tables are readable and correct.
3. Keep all information visible for character based readers.
Making everything look pretty is not as important.
If you find any errors or if you have any suggestions, please send mail to
andy.vesper@eng.pko.dec.com or andy.vesper@pko.mts.dec.com. I will try to fix
them up as I find time. Unfortunately this is a volunteer effort and I so I
cannot spend much time on it.
To start, choose either the alphabetic order page or specification order
page.
There is also an introductory page located at glXIntro.
The GLU tesselator has changed in GLU version 1.2; here are some notes on the
new GLU tesselator
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Due to popular demand, I have added a tar file and a zip file, each of which
contains all the .html sources. Note that the names are long names with the
extension .html, and so are not appropriate to being placed on a FAT-formatted
disk.
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
For more OpenGL information, I suggest starting at The OpenGL WWW Center.
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
You can also read the hypertext version of The OpenGL Graphics System: A
Specification (Version 1.1). In this document all formulae are given as
images, so they look much better than my ASCII art. However, this is Version
1.1, not Version 1.0. SGI does not seem to have kept the 1.0 version around.
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Last Edited: Wed Feb 5 10:37:39 EST 1997 by AFV
Look here for legal stuff: Legal
ΓòÉΓòÉΓòÉ 2. Andrew Frank Vesper, Business Card ΓòÉΓòÉΓòÉ
OpenGL man pages
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Andrew Frank Vesper
3D Graphics Group
Alpha Personal Systems
Internet: andy.vesper@eng.pko.dec.com
or: andy.vesper@pko.mts.dec.com
Digital Equipment Corporation
PKO3-1 / N30
129 Parker Street,
Maynard, MA 01754-2198
Telephone : 508-493-6315
FAX : 508-493-1227 -- Please call or send mail to alert me
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Last Edited: Fri Dec 6 11:18:03 EST 1996
ΓòÉΓòÉΓòÉ 3. OpenGL Index of routines in Alphabetic Order ΓòÉΓòÉΓòÉ
OpenGL man pages
Contents
glA glB glC glD glE glF glG glH glI glL glM glN glO glP glR glS glT glV glX glu
OpenGL Index in Alphabetic Order
glA...
glAccum
glAlphaFunc
glArrayElementEXT
glB...
glBegin
glBitmap
glBlendFunc
glC...
glCallList
glCallLists
glClear
glClearAccum
glClearColor
glClearDepth
glClearIndex
glClearStencil
glClipPlane
glColor3b, glColor3bv, glColor3d, glColor3dv, glColor3f, glColor3fv,
glColor3i, glColor3iv, glColor3s, glColor3sv, glColor3ub,
glColor3ubv, glColor3ui, glColor3uiv, glColor3us, glColor3usv,
glColor4b, glColor4bv, glColor4d, glColor4dv, glColor4f, glColor4fv,
glColor4i, glColor4iv, glColor4s, glColor4sv, glColor4ub,
glColor4ubv, glColor4ui, glColor4uiv, glColor4us, glColor4usv
glColorMask
glColorMaterial
glColorPointerEXT
glCopyPixels
glCullFace
glD...
glDeleteLists
glDepthFunc
glDepthMask
glDepthRange
glDisable
glDrawArraysEXT
glDrawBuffer
glDrawPixels
glE...
glEdgeFlag
glEdgeFlagPointerEXT
glEdgeFlagv
glEnable
glEnd
glEndList
glEvalCoord1d, glEvalCoord1dv, glEvalCoord1f, glEvalCoord1fv,
glEvalCoord2d, glEvalCoord2dv, glEvalCoord2f, glEvalCoord2fv
glEvalMesh1, glEvalMesh2
glEvalPoint1, glEvalPoint2
glF...
glFeedbackBuffer
glFinish
glFlush
glFogf, glFogfv, glFogi, glFogiv
glFrontFace
glFrustum
glG...
glGenLists
glGetBooleanv
glGetClipPlane
glGetDoublev
glGetError
glGetFloatv, glGetIntegerv
glGetLightfv, glGetLightiv
glGetMapdv, glGetMapfv, glGetMapiv
glGetMaterialfv, glGetMaterialiv
glGetPixelMapfv, glGetPixelMapuiv, glGetPixelMapusv
glGetPointervEXT
glGetPolygonStipple
glGetString
glGetTexEnvfv, glGetTexEnviv
glGetTexGendv, glGetTexGenfv, glGetTexGeniv
glGetTexImage
glGetTexLevelParameterfv, glGetTexLevelParameteriv
glGetTexParameterfv, glGetTexParameteriv
glH...
glHint
glI...
glIndexMask
glIndexPointerEXT
glIndexd, glIndexdv, glIndexf, glIndexfv, glIndexi, glIndexiv,
glIndexs, glIndexsv
glInitNames
glIsEnabled
glIsList
glL...
glLightModelf, glLightModelfv, glLightModeli, glLightModeliv
glLightf, glLightfv, glLighti, glLightiv
glLineStipple
glLineWidth
glListBase
glLoadIdentity
glLoadMatrixd, glLoadMatrixf
glLoadName
glLogicOp
glM...
glMap1d, glMap1f
glMap2d, glMap2f
glMapGrid1d, glMapGrid1f, glMapGrid2d, glMapGrid2f
glMaterialf, glMaterialfv, glMateriali, glMaterialiv
glMatrixMode
glMultMatrixd, glMultMatrixf
glN...
glNewList
glNormal3b, glNormal3bv, glNormal3d, glNormal3dv, glNormal3f,
glNormal3fv, glNormal3i, glNormal3iv, glNormal3s, glNormal3sv
glNormalPointerEXT
glO...
glOrtho
glP...
glPassThrough
glPixelMapfv, glPixelMapuiv, glPixelMapusv
glPixelStoref, glPixelStorei
glPixelTransferf, glPixelTransferi
glPixelZoom
glPointSize
glPolygonMode
glPolygonStipple
glPopAttrib
glPopMatrix
glPopName
glPushAttrib
glPushMatrix
glPushName
glR...
glRasterPos2d, glRasterPos2dv, glRasterPos2f, glRasterPos2fv,
glRasterPos2i, glRasterPos2iv, glRasterPos2s, glRasterPos2sv,
glRasterPos3d, glRasterPos3dv, glRasterPos3f, glRasterPos3fv,
glRasterPos3i, glRasterPos3iv, glRasterPos3s, glRasterPos3sv,
glRasterPos4d, glRasterPos4dv, glRasterPos4f, glRasterPos4fv,
glRasterPos4i, glRasterPos4iv, glRasterPos4s, glRasterPos4sv
glReadBuffer
glReadPixels
glRectd, glRectdv, glRectf, glRectfv, glRecti, glRectiv, glRects,
glRectsv
glRenderMode
glRotated glRotatef
glS...
glScaled, glScalef
glScissor
glSelectBuffer
glShadeModel
glStencilFunc
glStencilMask
glStencilOp
glT...
glTexCoord1d, glTexCoord1dv, glTexCoord1f, glTexCoord1fv,
glTexCoord1i, glTexCoord1iv, glTexCoord1s, glTexCoord1sv,
glTexCoord2d, glTexCoord2dv, glTexCoord2f, glTexCoord2fv,
glTexCoord2i, glTexCoord2iv, glTexCoord2s, glTexCoord2sv,
glTexCoord3d, glTexCoord3dv, glTexCoord3f, glTexCoord3fv,
glTexCoord3i, glTexCoord3iv, glTexCoord3s, glTexCoord3sv,
glTexCoord4d, glTexCoord4dv, glTexCoord4f, glTexCoord4fv,
glTexCoord4i, glTexCoord4iv, glTexCoord4s, glTexCoord4sv
glTexCoordPointerEXT,
glTexEnvf, glTexEnvfv, glTexEnvi, glTexEnviv,
glTexGend, glTexGendv, glTexGenf, glTexGenfv, glTexGeni, glTexGeniv
glTexImage1D
glTexImage2D
glTexParameterf, glTexParameterfv, glTexParameteri, glTexParameteriv
glTranslated, glTranslatef
glV...
glVertex2d, glVertex2dv, glVertex2f, glVertex2fv, glVertex2i,
glVertex2iv, glVertex2s, glVertex2sv, glVertex3d, glVertex3dv,
glVertex3f, glVertex3fv, glVertex3i, glVertex3iv, glVertex3s,
glVertex3sv, glVertex4d, glVertex4dv, glVertex4f, glVertex4fv,
glVertex4i, glVertex4iv, glVertex4s, glVertex4sv
glVertexPointerEXT
glViewport
glX...
glXChooseVisual
glXCopyContext
glXCreateContext
glXCreateGLXPixmap
glXDestroyContext
glXDestroyGLXPixmap
glXGetConfig
glXGetCurrentContext
glXGetCurrentDrawable
glXIsDirect
glXMakeCurrent
glXQueryExtension
glXQueryVersion
glXSwapBuffers
glXUseXFont
glXWaitGL
glXWaitX
glu...
See notes on the new GLU tesselator
gluBeginCurve
gluBeginPolygon (GLU versions 1.0 and 1.1)
gluBeginPolygon (GLU version 1.2 and later)
gluBeginSurface
gluBeginTrim
gluBuild1DMipmaps
gluBuild2DMipmaps
gluCylinder
gluDeleteNurbsRenderer
gluDeleteQuadric
gluDeleteTess (GLU versions 1.0 and 1.1)
gluDeleteTess (GLU version 1.2 and later)
gluDisk
gluEndCurve
gluEndPolygon (GLU versions 1.0 and 1.1)
gluEndPolygon (GLU version 1.2 and later)
gluEndSurface
gluEndTrim
gluErrorString
gluGetNurbsProperty
gluGetTessProperty (GLU version 1.2 and later)
gluLoadSamplingMatrices
gluLookAt
gluNewNurbsRenderer
gluNewQuadric
gluNewTess (GLU versions 1.0 and 1.1)
gluNewTess (GLU version 1.2 and later)
gluNextContour (GLU versions 1.0 and 1.1)
gluNextContour (GLU version 1.2 and later)
gluNurbsCallback
gluNurbsCurve
gluNurbsProperty
gluNurbsSurface
gluOrtho2D
gluPartialDisk
gluPerspective
gluPickMatrix
gluProject
gluPwlCurve
gluQuadricCallback
gluQuadricDrawStyle
gluQuadricNormals
gluQuadricOrientation
gluQuadricTexture
gluScaleImage
gluSphere
gluTessBeginContour (GLU version 1.2 and later)
gluTessBeginPolygon (GLU version 1.2 and later)
gluTessCallback (GLU versions 1.0 and 1.1)
gluTessCallback (GLU version 1.2 and later)
gluTessEndContour (GLU version 1.2 and later)
gluTessEndPolygon (GLU version 1.2 and later)
gluTessNormal (GLU version 1.2 and later)
gluTessProperty (GLU version 1.2 and later)
gluTessVertex (GLU versions 1.0 and 1.1)
gluTessVertex (GLU version 1.2 and later)
gluUnProject
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
Look here for legal stuff: Legal
ΓòÉΓòÉΓòÉ 3.1. glAccum ΓòÉΓòÉΓòÉ
OpenGL man pages
glAccum
Name
glAccum - operate on the accumulation buffer
C Specification
void glAccum( GLenum op,
GLfloat value )
Parameters
op Specifies the accumulation buffer operation. Symbolic constants
GL_ACCUM, GL_LOAD, GL_ADD, GL_MULT, and GL_RETURN are accepted.
value Specifies a floating-point value used in the accumulation buffer
operation. op determines how value is used.
Description
The accumulation buffer is an extended-range color buffer. Images are not
rendered into it. Rather, images rendered into one of the color buffers
are added to the contents of the accumulation buffer after rendering.
Effects such as antialiasing (of points, lines, and polygons), motion blur,
and depth of field can be created by accumulating images generated with
different transformation matrices.
Each pixel in the accumulation buffer consists of red, green, blue, and
alpha values. The number of bits per component in the accumulation buffer
depends on the implementation. You can examine this number by calling
glGetIntegerv four times, with arguments GL_ACCUM_RED_BITS,
GL_ACCUM_GREEN_BITS, GL_ACCUM_BLUE_BITS, and GL_ACCUM_ALPHA_BITS,
respectively. Regardless of the number of bits per component, however, the
range of values stored by each component is [-1, 1]. The accumulation
buffer pixels are mapped one-to-one with frame buffer pixels.
glAccum operates on the accumulation buffer. The first argument, op, is a
symbolic constant that selects an accumulation buffer operation. The
second argument, value, is a floating-point value to be used in that
operation. Five operations are specified: GL_ACCUM, GL_LOAD, GL_ADD,
GL_MULT, and GL_RETURN.
All accumulation buffer operations are limited to the area of the current
scissor box and are applied identically to the red, green, blue, and alpha
components of each pixel. The contents of an accumulation buffer pixel
component are undefined if the glAccum operation results in a value outside
the range [-1,1]. The operations are as follows:
GL_ACCUM Obtains R, G, B, and A values from the buffer currently selected
for reading (see glReadBuffer). Each component value is divided
by 2n-1, where n is the number of bits allocated to each color
component in the currently selected buffer. The result is a
floating-point value in the range [0,1], which is multiplied by
value and added to the corresponding pixel component in the
accumulation buffer, thereby updating the accumulation buffer.
GL_LOAD Similar to GL_ACCUM, except that the current value in the
accumulation buffer is not used in the calculation of the new
value. That is, the R, G, B, and A values from the currently
selected buffer are divided by 2n-1, multiplied by value, and
then stored in the corresponding accumulation buffer cell,
overwriting the current value.
GL_ADD Adds value to each R, G, B, and A in the accumulation buffer.
GL_MULT Multiplies each R, G, B, and A in the accumulation buffer by
value and returns the scaled component to its corresponding
accumulation buffer location.
GL_RETURN Transfers accumulation buffer values to the color buffer or
buffers currently selected for writing. Each R, G, B, and A
component is multiplied by value, then multiplied by 2n-1,
clamped to the range [0,2n-1], and stored in the corresponding
display buffer cell. The only fragment operations that are
applied to this transfer are pixel ownership, scissor, dithering,
and color writemasks.
The accumulation buffer is cleared by specifying R, G, B, and A values to
set it to with the glClearAccum directive, and issuing a glClear command
with the accumulation buffer enabled.
Notes
Only those pixels within the current scissor box are updated by any glAccum
operation.
Errors
GL_INVALID_ENUM is generated if op is not an accepted value.
GL_INVALID_OPERATION is generated if there is no accumulation buffer.
GL_INVALID_OPERATION is generated if glAccum is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_ACCUM_RED_BITS
glGet with argument GL_ACCUM_GREEN_BITS
glGet with argument GL_ACCUM_BLUE_BITS
glGet with argument GL_ACCUM_ALPHA_BITS
See Also
glBlendFunc, glClear, glClearAccum, glCopyPixels, glGet, glLogicOp,
glPixelStore, glPixelTransfer, glReadPixels, glReadBuffer, glScissor,
glStencilOp
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ΓòÉΓòÉΓòÉ 3.2. glAlphaFunc ΓòÉΓòÉΓòÉ
OpenGL man pages
glAlphaFunc
Name
glAlphaFunc - specify the alpha test function
C Specification
void glAlphaFunc( GLenum func,
GLclampf ref )
Parameters
func Specifies the alpha comparison function. Symbolic constants
GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL, GL_GREATER, GL_NOTEQUAL,
GL_GEQUAL, and GL_ALWAYS are accepted. The default function is
GL_ALWAYS.
ref Specifies the reference value that incoming alpha values are compared
to. This value is clamped to the range 0 through 1, where 0
represents the lowest possible alpha value and 1 the highest possible
value. The default reference is 0.
Description
The alpha test discards fragments depending on the outcome of a comparison
between the incoming fragment's alpha value and a constant reference value.
glAlphaFunc specifies the reference and comparison function. The
comparison is performed only if alpha testing is enabled. (See glEnable
and glDisable of GL_ALPHA_TEST.)
func and ref specify the conditions under which the pixel is drawn. The
incoming alpha value is compared to ref using the function specified by
func. If the comparison passes, the incoming fragment is drawn,
conditional on subsequent stencil and depth buffer tests. If the comparison
fails, no change is made to the frame buffer at that pixel location.
The comparison functions are as follows:
GL_NEVER Never passes.
GL_LESS Passes if the incoming alpha value is less than the
reference value.
GL_EQUAL Passes if the incoming alpha value is equal to the
reference value.
GL_LEQUAL Passes if the incoming alpha value is less than or equal
to the reference value.
GL_GREATER Passes if the incoming alpha value is greater than the
reference value.
GL_NOTEQUAL Passes if the incoming alpha value is not equal to the
reference value.
GL_GEQUAL Passes if the incoming alpha value is greater than or
equal to the reference value.
GL_ALWAYS Always passes.
glAlphaFunc operates on all pixel writes, including those resulting from
the scan conversion of points, lines, polygons, and bitmaps, and from pixel
draw and copy operations. glAlphaFunc does not affect screen clear
operations.
Notes
Alpha testing is done only in RGBA mode.
Errors
GL_INVALID_ENUM is generated if func is not an accepted value.
GL_INVALID_OPERATION is generated if glAlphaFunc is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_ALPHA_TEST_FUNC
glGet with argument GL_ALPHA_TEST_REF
glIsEnabled with argument GL_ALPHA_TEST
See Also
glBlendFunc, glClear, glDepthFunc, glEnable, glStencilFunc
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ΓòÉΓòÉΓòÉ 3.3. glArrayElementEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glArrayElementEXT
Name
glArrayElementEXT - specify the array elements used to render a vertex
C Specification
void glArrayElementEXT( GLint i )
Parameters
i Specifies an index in the enabled arrays.
Description
glArrayElementEXT commands are used within glBegin/glEnd pairs to specify
vertex and attribute data for point, line and polygon primitives. When
glArrayElementEXT is called, a single vertex is drawn, using vertex and
attribute data taken from location i of the enabled arrays.
Use glArrayElementEXT to construct primitives by indexing vertex data,
rather than by streaming through arrays of data in first-to-last order.
Because each call specifies only a single vertex, it is possible to
explicitly specify per-primitive attributes, such as a single normal per
individual triangle.
Notes
glArrayElementEXT may be included in display lists. If glArrayElementEXT is
entered into a display list, the necessary array data (determined by the
array pointers and enables) is also entered into the display list. Because
the array pointers and enables are client side state, their values affect
display lists when the lists are created, not when the lists are executed.
Static array data may be read and cached by the implementation at any time.
If static array elements are modified and the arrays are not respecified,
the results of any subsequent calls to glArrayElementEXT are undefined.
glArrayElementEXT executes even if GL_VERTEX_ARRAY_EXT is not enabled. No
drawing occurs in this case, but the attributes corresponding to enabled
arrays are modified.
Although it is not an error to respecify an array between the execution of
glBegin and the corresponding execution of glEnd, the result of such
respecification is undefined.
glArrayElementEXT is part of the EXT_vertex_array extension, not
part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
See Also
glColorPointerEXT, glDrawArraysEXT, glEdgeFlagPointerEXT, glGetPointervEXT,
glIndexPointerEXT, glNormalPointerEXT, glTexCoordPointerEXT,
glVertexPointerEXT
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ΓòÉΓòÉΓòÉ 3.4. glBegin ΓòÉΓòÉΓòÉ
OpenGL man pages
glBegin
Name
glBegin, glEnd - delimit the vertices of a primitive or a group of like
primitives
C Specification
void glBegin( GLenum mode )
Parameters
mode Specifies the primitive or primitives that will be created from
vertices presented between glBegin and the subsequent glEnd. Ten
symbolic constants are accepted: GL_POINTS, GL_LINES, GL_LINE_STRIP,
GL_LINE_LOOP, GL_TRIANGLES, GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN,
GL_QUADS, GL_QUAD_STRIP, and GL_POLYGON.
C Specification
void glEnd( void )
Description
glBegin and glEnd delimit the vertices that define a primitive or a group
of like primitives. glBegin accepts a single argument that specifies which
of ten ways the vertices are interpreted. Taking n as an integer count
starting at one, and N as the total number of vertices specified, the
interpretations are as follows:
GL_POINTS Treats each vertex as a single point. Vertex n defines point n.
N points are drawn.
GL_LINES Treates each pair of vertices as an independent line segment.
Vertices 2n-1 and 2n define line n. N/2 lines are drawn.
GL_LINE_STRIP
Draws a connected group of line segments from the first vertex to
the last. Vertices n and n+1 define line n. N-1 lines are
drawn.
GL_LINE_LOOP
Draws a connected group of line segments from the first vertex to
the last, then back to the first. Vertices n and n+1 define line
n. The last line, however, is defined by vertices N and 1. N
lines are drawn.
GL_TRIANGLES
Treates each triplet of vertices as an independent triangle.
Vertices 3n-2, 3n-1, and 3n define triangle n. N/3 triangles are
drawn.
GL_TRIANGLE_STRIP
Draws a connected group of triangles. One triangle is defined
for each vertex presented after the first two vertices. For odd
n, vertices n, n+1, and n+2 define triangle n. For even n,
vertices n+1, n, and n+2 define triangle n. N-2 triangles are
drawn.
GL_TRIANGLE_FAN
Draws a connected group of triangles. One triangle is defined
for each vertex presented after the first two vertices. Vertices
1, n+1, and n+2 define triangle n. N-2 triangles are drawn.
GL_QUADS Treats each group of four vertices as an independent
quadrilateral. Vertices 4n-3, 4n-2, 4n-1, and 4n define
quadrilateral n. N/4 quadrilaterals are drawn.
GL_QUAD_STRIP
Draws a connected group of quadrilaterals. One quadrilateral is
defined for each pair of vertices presented after the first pair.
Vertices 2n-1, 2n, 2n+2, and 2n+1 define quadrilateral n. N/2-1
quadrilaterals are drawn. Note that the order in which vertices
are used to construct a quadrilateral from strip data is
different from that used with independent data.
GL_POLYGON
Draws a single, convex polygon. Vertices 1 through N define this
polygon.
Only a subset of GL commands can be used between glBegin and glEnd. The
commands are glVertex, glColor, glIndex, glNormal, glTexCoord,
glEvalCoord,
glEvalPoint, glMaterial, and glEdgeFlag. Also, it is acceptable to use
glCallList or glCallLists to execute display lists that include only the
preceding commands. If any other GL command is executed between glBegin
and glEnd, the error flag is set and the command is ignored.
Regardless of the value chosen for mode, there is no limit to the number of
vertices that can be defined between glBegin and glEnd. Lines, triangles,
quadrilaterals, and polygons that are incompletely specified are not drawn.
Incomplete specification results when either too few vertices are provided
to specify even a single primitive or when an incorrect multiple of
vertices is specified. The incomplete primitive is ignored; the rest are
drawn.
The minimum specification of vertices for each primitive is as follows: 1
for a point, 2 for a line, 3 for a triangle, 4 for a quadrilateral, and 3
for a polygon. Modes that require a certain multiple of vertices are
GL_LINES (2), GL_TRIANGLES (3), GL_QUADS (4), and GL_QUAD_STRIP (2).
Errors
GL_INVALID_ENUM is generated if mode is set to an unaccepted value.
GL_INVALID_OPERATION is generated if a command other than glVertex,
glColor, glIndex, glNormal, glTexCoord, glEvalCoord, glEvalPoint,
glMaterial, glEdgeFlag, glCallList, or glCallLists is executed between
glBegin and the corresponding glEnd.
GL_INVALID_OPERATION is generated if a glBegin is executed between a
glBegin and the corresponding execution of glEnd.
GL_INVALID_OPERATION is generated if glEnd is executed without being
preceded by a glBegin.
See Also
glCallList, glCallLists, glColor, glEdgeFlag, glEvalCoord, glEvalPoint,
glIndex, glMaterial, glNormal, glTexCoord, glVertex
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ΓòÉΓòÉΓòÉ 3.5. glBitmap ΓòÉΓòÉΓòÉ
OpenGL man pages
glBitmap
Name
glBitmap - draw a bitmap
C Specification
void glBitmap( GLsizei width,
GLsizei height,
GLfloat xorig,
GLfloat yorig,
GLfloat xmove,
GLfloat ymove,
const GLubyte *bitmap )
Parameters
width, height Specify the pixel width and height of the bitmap image.
xorig, yorig Specify the location of the origin in the bitmap image. The
origin is measured from the lower left corner of the bitmap,
with right and up being the positive axes.
xmove, ymove Specify the x and y offsets to be added to the current raster
position after the bitmap is drawn.
bitmap Specifies the address of the bitmap image.
Description
A bitmap is a binary image. When drawn, the bitmap is positioned relative
to the current raster position, and frame buffer pixels corresponding to
ones in the bitmap are written using the current raster color or index.
Frame buffer pixels corresponding to zeros in the bitmap are not modified.
glBitmap takes seven arguments. The first pair specify the width and
height of the bitmap image. The second pair specify the location of the
bitmap origin relative to the lower left corner of the bitmap image. The
third pair of arguments specify x and y offsets to be added to the current
raster position after the bitmap has been drawn. The final argument is a
pointer to the bitmap image itself.
The bitmap image is interpreted like image data for the glDrawPixels
command, with width and height corresponding to the width and height
arguments of that command, and with type set to GL_BITMAP and format set to
GL_COLOR_INDEX. Modes specified using glPixelStore affect the
interpretation of bitmap image data; modes specified using glPixelTransfer
do not.
If the current raster position is invalid, glBitmap is ignored. Otherwise,
the lower left corner of the bitmap image is positioned at the window
coordinates
x = floor (x - x )
w r o
y = floor (y - y )
w r o
where (x ,y ) is the raster position and (x ,y ) is the bitmap origin.
r r o o
Fragments are then generated for each pixel corresponding to a one in the
bitmap image. These fragments are generated using the current raster z
coordinate, color or color index, and current raster texture coordinates.
They are then treated just as if they had been generated by a point, line,
or polygon, including texture mapping, fogging, and all per-fragment
operations such as alpha and depth testing.
After the bitmap has been drawn, the x and y coordinates of the current
raster position are offset by xmove and ymove. No change is made to the z
coordinate of the current raster position, or to the current raster color,
index, or texture coordinates.
Errors
GL_INVALID_VALUE is generated if width or height is negative.
GL_INVALID_OPERATION is generated if glBitmap is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_CURRENT_RASTER_POSITION
glGet with argument GL_CURRENT_RASTER_COLOR
glGet with argument GL_CURRENT_RASTER_INDEX
glGet with argument GL_CURRENT_RASTER_TEXTURE_COORDS
glGet with argument GL_CURRENT_RASTER_POSITION_VALID
See Also
glDrawPixels, glRasterPos, glPixelStore, glPixelTransfer
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ΓòÉΓòÉΓòÉ 3.6. glBlendFunc ΓòÉΓòÉΓòÉ
OpenGL man pages
glBlendFunc
Name
glBlendFunc - specify pixel arithmetic
C Specification
void glBlendFunc( GLenum sfactor,
GLenum dfactor )
Parameters
sfactor Specifies how the red, green, blue, and alpha source blending
factors are computed. Nine symbolic constants are accepted:
GL_ZERO, GL_ONE, GL_DST_COLOR, GL_ONE_MINUS_DST_COLOR,
GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA,
GL_ONE_MINUS_DST_ALPHA, and GL_SRC_ALPHA_SATURATE.
dfactor Specifies how the red, green, blue, and alpha destination blending
factors are computed. Eight symbolic constants are accepted:
GL_ZERO, GL_ONE, GL_SRC_COLOR, GL_ONE_MINUS_SRC_COLOR,
GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA, and
GL_ONE_MINUS_DST_ALPHA.
Description
In RGB mode, pixels can be drawn using a function that blends the incoming
(source) RGBA values with the RGBA values that are already in the frame
buffer (the destination values). By default, blending is disabled. Use
glEnable and glDisable with argument GL_BLEND to enable and disable
blending.
glBlendFunc defines the operation of blending when it is enabled. sfactor
specifies which of nine methods is used to scale the source color
components. dfactor specifies which of eight methods is used to scale the
destination color components. The eleven possible methods are described in
the table below. Each method defines four scale factors, one each for red,
green, blue, and alpha.
In the table and in subsequent equations, source and destination color
components are referred to as (R ,G ,B ,A ) and (R ,G ,B ,A ). They are
s s s s d d d d
understood to have integer values between zero and (k ,k ,k ,k ), where
R G B A
mc
k = 2 - 1
c
and (mR,mG,mB,mA) is the number of red, green, blue, and alpha bitplanes.
Source and destination scale factors are referred to as (s ,s ,s ,s ) and
R G B A
(d ,d ,d ,d ). The scale factors described in the table, denoted
R G B A
(f ,f ,f ,f ), represent either source or destination factors. All scale
R G B A
factors have range [0,1].
-----------------------------------------------------------------------
| parameter | (f , f , f , f ) |
| | R G B A |
-----------------------------------------------------------------------
| | |
| GL_ZERO | (0, 0, 0, 0) |
| | |
| GL_ONE | (1, 1, 1, 1) |
| | |
| GL_SRC_COLOR | (R /k , G /k , B /k , A /k ) |
| | s R s G s B s A |
| | |
|GL_ONE_MINUS_SRC_COLOR | (1, 1, 1, 1) - (R /k , G /k , B /k , A /k ) |
| | s R s G s B s A |
| | |
| GL_DST_COLOR | (R /k , G /k , B /k , A /k ) |
| | d R d G d B d A |
| | |
|GL_ONE_MINUS_DST_COLOR | (1, 1, 1, 1) - (R /k , G /k , B /k , A /k ) |
| | d R d G d B d A |
| | |
| GL_SRC_ALPHA | (A /k , A /k , A /k , A /k ) |
| | s R s G s B s A |
| | |
| | |
|GL_ONE_MINUS_SRC_ALPHA | (1, 1, 1, 1) - (A /k , A /k , A /k , A /k ) |
| | s R s G s B s A |
| | |
| | |
| GL_DST_ALPHA | (A /k , A /k , A /k , A /k ) |
| | d R d G d B d A |
| | |
|GL_ONE_MINUS_DST_ALPHA | (1, 1, 1, 1) - (A /k , A /k , A /k , A /k ) |
| | d R d G d B d A |
| | |
| | |
|GL_SRC_ALPHA_SATURATE | (i, i, i, 1) |
| | |
-----------------------------------------------------------------------
In the table,
i = min(A , k -A ) / k
s A d A
To determine the blended RGBA values of a pixel when drawing in RGB mode,
the system uses the following equations:
R = min(k , R s +R d )
d R s R d R
G = min(k , G s +G d )
d G s G d G
B = min(k , B s +B d )
d B s B d B
A = min(k , A s +A d )
d A s A d A
Despite the apparent precision of the above equations, blending arithmetic
is not exactly specified, because blending operates with imprecise integer
color values. However, a blend factor that should be equal to one is
guaranteed not to modify its multiplicand, and a blend factor equal to zero
reduces its multiplicand to zero. Thus, for example, when sfactor is
GL_SRC_ALPHA, dfactor is GL_ONE_MINUS_SRC_ALPHA, and A is equal to k the
s A
equations reduce to simple replacement:
R = R
d s
G = G
d s
B = B
d s
A = A
d s
Examples
Transparency is best implemented using blend function (GL_SRC_ALPHA,
GL_ONE_MINUS_SRC_ALPHA) with primitives sorted from farthest to nearest.
Note that this transparency calculation does not require the presence of
alpha bitplanes in the frame buffer.
Blend function (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA) is also useful for
rendering antialiased points and lines in arbitrary order.
Polygon antialiasing is optimized using blend function
(GL_SRC_ALPHA_SATURATE, GL_ONE) with polygons sorted from nearest to
farthest. (See the glEnable, glDisable reference page and the
GL_POLYGON_SMOOTH argument for information on polygon antialiasing.)
Destination alpha bitplanes, which must be present for this blend function
to operate correctly, store the accumulated coverage.
Notes
Incoming (source) alpha is correctly thought of as a material opacity,
ranging from 1.0 (K ), representing complete opacity, to 0.0 (0),
A
representing complete transparency.
When more than one color buffer is enabled for drawing, blending is done
separately for each enabled buffer, using for destination color the
contents of that buffer. (See glDrawBuffer.)
Blending affects only RGB rendering. It is ignored by color index
renderers.
Errors
GL_INVALID_ENUM is generated if either sfactor or dfactor is not an
accepted value.
GL_INVALID_OPERATION is generated if glBlendFunc is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_BLEND_SRC
glGet with argument GL_BLEND_DST
glIsEnabled with argument GL_BLEND
See Also
glAlphaFunc, glClear, glDrawBuffer, glEnable, glLogicOp, glStencilFunc
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ΓòÉΓòÉΓòÉ 3.7. glCallList ΓòÉΓòÉΓòÉ
OpenGL man pages
glCallList
Name
glCallList - execute a display list
C Specification
void glCallList( GLuint list )
Parameters
list Specifies the integer name of the display list to be executed.
Description
glCallList causes the named display list to be executed. The commands
saved in the display list are executed in order, just as if they were
called without using a display list. If list has not been defined as a
display list, glCallList is ignored.
glCallList can appear inside a display list. To avoid the possibility of
infinite recursion resulting from display lists calling one another, a
limit is placed on the nesting level of display lists during display-list
execution. This limit is at least 64, and it depends on the
implementation.
GL state is not saved and restored across a call to glCallList. Thus,
changes made to GL state during the execution of a display list remain
after execution of the display list is completed. Use glPushAttrib,
glPopAttrib, glPushMatrix, and glPopMatrix to preserve GL state across
glCallList calls.
Notes
Display lists can be executed between a call to glBegin and the
corresponding call to glEnd, as long as the display list includes only
commands that are allowed in this interval.
Associated Gets
glGet with argument GL_MAX_LIST_NESTING
glIsList
See Also
glCallLists, glDeleteLists, glGenLists, glNewList, glPushAttrib,
glPushMatrix
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ΓòÉΓòÉΓòÉ 3.8. glCallLists ΓòÉΓòÉΓòÉ
OpenGL man pages
glCallLists
Name
glCallLists - execute a list of display lists
C Specification
void glCallLists( GLsizei n,
GLenum type,
const GLvoid *lists )
Parameters
n Specifies the number of display lists to be executed.
type Specifies the type of values in lists. Symbolic constants GL_BYTE,
GL_UNSIGNED_BYTE, GL_SHORT, GL_UNSIGNED_SHORT, GL_INT,
GL_UNSIGNED_INT, GL_FLOAT, GL_2_BYTES, GL_3_BYTES, and GL_4_BYTES
are accepted.
lists Specifies the address of an array of name offsets in the display
list. The pointer type is void because the offsets can be bytes,
shorts, ints, or floats, depending on the value of type.
Description
glCallLists causes each display list in the list of names passed as lists
to be executed. As a result, the commands saved in each display list are
executed in order, just as if they were called without using a display
list. Names of display lists that have not been defined are ignored.
glCallLists provides an efficient means for executing display lists. type
allows lists with various name formats to be accepted. The formats are as
follows:
GL_BYTE lists is treated as an array of signed bytes, each
in the range -128 through 127.
GL_UNSIGNED_BYTE lists is treated as an array of unsigned bytes,
each in the range 0 through 255.
GL_SHORT lists is treated as an array of signed two-byte
integers, each in the range -32768 through 32767.
GL_UNSIGNED_SHORT lists is treated as an array of unsigned two-byte
integers, each in the range 0 through 65535.
GL_INT lists is treated as an array of signed four-byte
integers.
GL_UNSIGNED_INT lists is treated as an array of unsigned four-byte
integers.
GL_FLOAT lists is treated as an array of four-byte
floating-point values.
GL_2_BYTES lists is treated as an array of unsigned bytes.
Each pair of bytes specifies a single display-list
name. The value of the pair is computed as 256
times the unsigned value of the first byte plus
the unsigned value of the second byte.
GL_3_BYTES lists is treated as an array of unsigned bytes.
Each triplet of bytes specifies a single display-
list name. The value of the triplet is computed
as 65536 times the unsigned value of the first
byte, plus 256 times the unsigned value of the
second byte, plus the unsigned value of the third
byte.
GL_4_BYTES lists is treated as an array of unsigned bytes.
Each quadruplet of bytes specifies a single
display-list name. The value of the quadruplet is
computed as 16777216 times the unsigned value of
the first byte, plus 65536 times the unsigned
value of the second byte, plus 256 times the
unsigned value of the third byte, plus the
unsigned value of the fourth byte.
The list of display list names is not null-terminated. Rather, n specifies
how many names are to be taken from lists.
An additional level of indirection is made available with the glListBase
command, which specifies an unsigned offset that is added to each display-
list name specified in lists before that display list is executed.
glCallLists can appear inside a display list. To avoid the possibility of
infinite recursion resulting from display lists calling one another, a
limit is placed on the nesting level of display lists during display-list
execution. This limit must be at least 64, and it depends on the
implementation.
GL state is not saved and restored across a call to glCallLists. Thus,
changes made to GL state during the execution of the display lists remain
after execution is completed. Use glPushAttrib, glPopAttrib, glPushMatrix,
and glPopMatrix to preserve GL state across glCallLists calls.
Notes
Display lists can be executed between a call to glBegin and the
corresponding call to glEnd, as long as the display list includes only
commands that are allowed in this interval.
Errors
GL_INVALID_VALUE is generated if n is negative.
GL_INVALID_ENUM is generated if type is not one of GL_BYTE,
GL_UNSIGNED_BYTE, GL_SHORT, GL_UNSIGNED_SHORT, GL_INT, GL_UNSIGNED_INT,
GL_FLOAT, GL_2_BYTES, GL_3_BYTES, GL_4_BYTES.
Associated Gets
glGet with argument GL_LIST_BASE
glGet with argument GL_MAX_LIST_NESTING
glIsList
See Also
glCallList, glDeleteLists, glGenLists, glListBase, glNewList, glPushAttrib,
glPushMatrix
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ΓòÉΓòÉΓòÉ 3.9. glClear ΓòÉΓòÉΓòÉ
OpenGL man pages
glClear
Name
glClear - clear buffers to preset values
C Specification
void glClear( GLbitfield mask )
Parameters
mask Bitwise OR of masks that indicate the buffers to be cleared. The
four masks are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT,
GL_ACCUM_BUFFER_BIT, and GL_STENCIL_BUFFER_BIT.
Description
glClear sets the bitplane area of the window to values previously selected
by glClearColor, glClearIndex, glClearDepth, glClearStencil, and
glClearAccum. Multiple color buffers can be cleared simultaneously by
selecting more than one buffer at a time using glDrawBuffer.
The pixel ownership test, the scissor test, dithering, and the buffer
writemasks affect the operation of glClear. The scissor box bounds the
cleared region. Alpha function, blend function, logical operation,
stenciling, texture mapping, and z-buffering are ignored by glClear.
glClear takes a single argument that is the bitwise OR of several values
indicating which buffer is to be cleared.
The values are as follows:
GL_COLOR_BUFFER_BIT Indicates the buffers currently enabled for
color writing.
GL_DEPTH_BUFFER_BIT Indicates the depth buffer.
GL_ACCUM_BUFFER_BIT Indicates the accumulation buffer.
GL_STENCIL_BUFFER_BIT Indicates the stencil buffer.
The value to which each buffer is cleared depends on the setting of the
clear value for that buffer.
Notes
If a buffer is not present, then a glClear directed at that buffer has no
effect.
Errors
GL_INVALID_VALUE is generated if any bit other than the four defined bits
is set in mask.
GL_INVALID_OPERATION is generated if glClear is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_ACCUM_CLEAR_VALUE
glGet with argument GL_DEPTH_CLEAR_VALUE
glGet with argument GL_INDEX_CLEAR_VALUE
glGet with argument GL_COLOR_CLEAR_VALUE
glGet with argument GL_STENCIL_CLEAR_VALUE
See Also
glClearAccum, glClearColor, glClearDepth, glClearIndex, glClearStencil,
glDrawBuffer, glScissor
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ΓòÉΓòÉΓòÉ 3.10. glClearAccum ΓòÉΓòÉΓòÉ
OpenGL man pages
glClearAccum
Name
glClearAccum - specify clear values for the accumulation buffer
C Specification
void glClearAccum( GLfloat red,
GLfloat green,
GLfloat blue,
GLfloat alpha )
Parameters
red, green, blue, alpha
Specify the red, green, blue, and alpha values used
when the accumulation buffer is cleared. The default
values are all zero.
Description
glClearAccum specifies the red, green, blue, and alpha values used by
glClear to clear the accumulation buffer.
Values specified by glClearAccum are clamped to the range [-1,1].
Errors
GL_INVALID_OPERATION is generated if glClearAccum is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_ACCUM_CLEAR_VALUE
See Also
glClear
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ΓòÉΓòÉΓòÉ 3.11. glClearColor ΓòÉΓòÉΓòÉ
OpenGL man pages
glClearColor
Name
glClearColor - specify clear values for the color buffers
C Specification
void glClearColor( GLclampf red,
GLclampf green,
GLclampf blue,
GLclampf alpha )
Parameters
red, green, blue, alpha
Specify the red, green, blue, and alpha values used
when the color buffers are cleared. The default
values are all zero.
Description
glClearColor specifies the red, green, blue, and alpha values used by
glClear to clear the color buffers. Values specified by glClearColor are
clamped to the range [0,1].
Errors
GL_INVALID_OPERATION is generated if glClearColor is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_COLOR_CLEAR_VALUE
See Also
glClear
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ΓòÉΓòÉΓòÉ 3.12. glClearDepth ΓòÉΓòÉΓòÉ
OpenGL man pages
glClearDepth
Name
glClearDepth - specify the clear value for the depth buffer
C Specification
void glClearDepth( GLclampd depth )
Parameters
depth Specifies the depth value used when the depth buffer is cleared.
Description
glClearDepth specifies the depth value used by glClear to clear the depth
buffer. Values specified by glClearDepth are clamped to the range [0,1].
Errors
GL_INVALID_OPERATION is generated if glClearDepth is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_DEPTH_CLEAR_VALUE
See Also
glClear
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ΓòÉΓòÉΓòÉ 3.13. glClearIndex ΓòÉΓòÉΓòÉ
OpenGL man pages
glClearIndex
Name
glClearIndex - specify the clear value for the color index buffers
C Specification
void glClearIndex( GLfloat c )
Parameters
c Specifies the index used when the color index buffers are cleared. The
default value is zero.
Description
glClearIndex specifies the index used by glClear to clear the color index
buffers. c is not clamped. Rather, c is converted to a fixed-point value
with unspecified precision to the right of the binary point. The integer
part of this value is then masked with 2m-1, where m is the number of bits
in a color index stored in the frame buffer.
Errors
GL_INVALID_OPERATION is generated if glClearIndex is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_INDEX_CLEAR_VALUE
glGet with argument GL_INDEX_BITS
See Also
glClear
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ΓòÉΓòÉΓòÉ 3.14. glClearStencil ΓòÉΓòÉΓòÉ
OpenGL man pages
glClearStencil
Name
glClearStencil - specify the clear value for the stencil buffer
C Specification
void glClearStencil( GLint s )
Parameters
s Specifies the index used when the stencil buffer is cleared. The
default value is zero.
Description
glClearStencil specifies the index used by glClear to clear the stencil
buffer. s is masked with 2m-1, where m is the number of bits in the
stencil buffer.
Errors
GL_INVALID_OPERATION is generated if glClearStencil is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_STENCIL_CLEAR_VALUE
glGet with argument GL_STENCIL_BITS
See Also
glClear
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ΓòÉΓòÉΓòÉ 3.15. glClipPlane ΓòÉΓòÉΓòÉ
OpenGL man pages
glClipPlane
Name
glClipPlane - specify a plane against which all geometry is clipped
C Specification
void glClipPlane( GLenum plane,
const GLdouble *equation )
Parameters
plane Specifies which clipping plane is being positioned. Symbolic
names of the form GL_CLIP_PLANEi, where i is an integer between 0
and GL_MAX_CLIP_PLANES -1, are accepted.
equation Specifies the address of an array of four double-precision
floating-point values. These values are interpreted as a plane
equation.
Description
Geometry is always clipped against the boundaries of a six-plane frustum in
x, y, and z. glClipPlane allows the specification of additional planes, not
necessarily perpendicular to the x, y, or z axis, against which all
geometry is clipped. Up to GL_MAX_CLIP_PLANES planes can be specified,
where GL_MAX_CLIP_PLANES is at least six in all implementations. Because
the resulting clipping region is the intersection of the defined half-
spaces, it is always convex.
glClipPlane specifies a half-space using a four-component plane equation.
When glClipPlane is called, equation is transformed by the inverse of the
modelview matrix and stored in the resulting eye coordinates. Subsequent
changes to the modelview matrix have no effect on the stored plane-equation
components. If the dot product of the eye coordinates of a vertex with the
stored plane equation components is positive or zero, the vertex is in with
respect to that clipping plane. Otherwise, it is out.
Clipping planes are enabled and disabled with glEnable and glDisable, and
called with the argument GL_CLIP_PLANEi, where i is the plane number.
By default, all clipping planes are defined as (0,0,0,0) in eye coordinates
and are disabled.
Notes
It is always the case that GL_CLIP_PLANEi = GL_CLIP_PLANE0 + i.
Errors
GL_INVALID_ENUM is generated if plane is not an accepted value.
GL_INVALID_OPERATION is generated if glClipPlane is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetClipPlane
glIsEnabled with argument GL_CLIP_PLANEi
See Also
glEnable
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ΓòÉΓòÉΓòÉ 3.16. glColor ΓòÉΓòÉΓòÉ
OpenGL man pages
glColor
Name
glColor3b, glColor3d, glColor3f, glColor3i, glColor3s,
glColor3ub,
glColor3ui, glColor3us, glColor4b, glColor4d, glColor4f,
glColor4i,
glColor4s, glColor4ub, glColor4ui, glColor4us, glColor3bv,
glColor3dv,
glColor3fv, glColor3iv, glColor3sv, glColor3ubv, glColor3uiv,
glColor3usv,
glColor4bv, glColor4dv, glColor4fv, glColor4iv, glColor4sv,
glColor4ubv,
glColor4uiv, glColor4usv - set the current color
C Specification
void glColor3b( GLbyte red,
GLbyte green,
GLbyte blue )
void glColor3d( GLdouble red,
GLdouble green,
GLdouble blue )
void glColor3f( GLfloat red,
GLfloat green,
GLfloat blue )
void glColor3i( GLint red,
GLint green,
GLint blue )
void glColor3s( GLshort red,
GLshort green,
GLshort blue )
void glColor3ub( GLubyte red,
GLubyte green,
GLubyte blue )
void glColor3ui( GLuint red,
GLuint green,
GLuint blue )
void glColor3us( GLushort red,
GLushort green,
GLushort blue )
void glColor4b( GLbyte red,
GLbyte green,
GLbyte blue,
GLbyte alpha )
void glColor4d( GLdouble red,
GLdouble green,
GLdouble blue,
GLdouble alpha )
void glColor4f( GLfloat red,
GLfloat green,
GLfloat blue,
GLfloat alpha )
void glColor4i( GLint red,
GLint green,
GLint blue,
GLint alpha )
void glColor4s( GLshort red,
GLshort green,
GLshort blue,
GLshort alpha )
void glColor4ub( GLubyte red,
GLubyte green,
GLubyte blue,
GLubyte alpha )
void glColor4ui( GLuint red,
GLuint green,
GLuint blue,
GLuint alpha )
void glColor4us( GLushort red,
GLushort green,
GLushort blue,
GLushort alpha )
Parameters
red, green, blue
Specify new red, green, and blue values for the current
color.
alpha Specifies a new alpha value for the current color.
Included only in the four-argument glColor4 command.
C Specification
void glColor3bv( const GLbyte *v )
void glColor3dv( const GLdouble *v )
void glColor3fv( const GLfloat *v )
void glColor3iv( const GLint *v )
void glColor3sv( const GLshort *v )
void glColor3ubv( const GLubyte *v )
void glColor3uiv( const GLuint *v )
void glColor3usv( const GLushort *v )
void glColor4bv( const GLbyte *v )
void glColor4dv( const GLdouble *v )
void glColor4fv( const GLfloat *v )
void glColor4iv( const GLint *v )
void glColor4sv( const GLshort *v )
void glColor4ubv( const GLubyte *v )
void glColor4uiv( const GLuint *v )
void glColor4usv( const GLushort *v )
Parameters
v Specifies a pointer to an array that contains red, green, blue, and
(sometimes) alpha values.
Description
The GL stores both a current single-valued color index and a current four-
valued RGBA color. glColor sets a new four-valued RGBA color. glColor has
two major variants: glColor3 and glColor4. glColor3 variants specify new
red, green, and blue values explicitly, and set the current alpha value to
1.0 implicitly. glColor4 variants specify all four color components
explicitly.
glColor3b, glColor4b, glColor3s, glColor4s, glColor3i, and
glColor4i take
three or four signed byte, short, or long integers as arguments. When v is
appended to the name, the color commands can take a pointer to an array of
such values.
Current color values are stored in floating-point format, with unspecified
mantissa and exponent sizes. Unsigned integer color components, when
specified, are linearly mapped to floating-point values such that the
largest representable value maps to 1.0 (full intensity), and zero maps to
0.0 (zero intensity). Signed integer color components, when specified, are
linearly mapped to floating-point values such that the most positive
representable value maps to 1.0, and the most negative representable value
maps to -1.0. Floating-point values are mapped directly.
Neither floating-point nor signed integer values are clamped to the range
[0,1] before updating the current color. However, color components are
clamped to this range before they are interpolated or written into a color
buffer.
Notes
The current color can be updated at any time. In particular, glColor can
be called between a call to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_CURRENT_COLOR
glGet with argument GL_RGBA_MODE
See Also
glIndex
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ΓòÉΓòÉΓòÉ 3.17. glColorMask ΓòÉΓòÉΓòÉ
OpenGL man pages
glColorMask
Name
glColorMask - enable and disable writing of frame buffer color components
C Specification
void glColorMask( GLboolean red,
GLboolean green,
GLboolean blue,
GLboolean alpha )
Parameters
red, green, blue, alpha
Specify whether red, green, blue, and alpha can or
cannot be written into the frame buffer. The default
values are all GL_TRUE, indicating that the color
components can be written.
Description
glColorMask specifies whether the individual color components in the frame
buffer can or cannot be written. If red is GL_FALSE, for example, no
change is made to the red component of any pixel in any of the color
buffers, regardless of the drawing operation attempted.
Changes to individual bits of components cannot be controlled. Rather,
changes are either enabled or disabled for entire color components.
Errors
GL_INVALID_OPERATION is generated if glColorMask is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_COLOR_WRITEMASK
glGet with argument GL_RGBA_MODE
See Also
glColor, glIndex, glIndexMask, glDepthMask, glStencilMask
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ΓòÉΓòÉΓòÉ 3.18. glColorMaterial ΓòÉΓòÉΓòÉ
OpenGL man pages
glColorMaterial
Name
glColorMaterial - cause a material color to track the current color
C Specification
void glColorMaterial( GLenum face,
GLenum mode )
Parameters
face Specifies whether front, back, or both front and back material
parameters should track the current color. Accepted values are
GL_FRONT, GL_BACK, and GL_FRONT_AND_BACK. The default value is
GL_FRONT_AND_BACK.
mode Specifies which of several material parameters track the current
color. Accepted values are GL_EMISSION, GL_AMBIENT, GL_DIFFUSE,
GL_SPECULAR, and GL_AMBIENT_AND_DIFFUSE. The default value is
GL_AMBIENT_AND_DIFFUSE.
Description
glColorMaterial specifies which material parameters track the current
color. When GL_COLOR_MATERIAL is enabled, the material parameter or
parameters specified by mode, of the material or materials specified by
face, track the current color at all times. GL_COLOR_MATERIAL is enabled
and disabled using the commands glEnable and glDisable, called with
GL_COLOR_MATERIAL as their argument. By default, it is disabled.
Notes
glColorMaterial allows a subset of material parameters to be changed for
each vertex using only the glColor command, without calling glMaterial. If
only such a subset of parameters is to be specified for each vertex,
glColorMaterial is preferred over calling glMaterial.
Call glColorMaterial before enabling the GL_COLOR_MATERIAL.
Errors
GL_INVALID_ENUM is generated if face or mode is not an accepted value.
GL_INVALID_OPERATION is generated if glColorMaterial is executed between
the execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glIsEnabled with argument GL_COLOR_MATERIAL
glGet with argument GL_COLOR_MATERIAL_PARAMETER
glGet with argument GL_COLOR_MATERIAL_FACE
See Also
glColor, glEnable, glLight, glLightModel, glMaterial
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ΓòÉΓòÉΓòÉ 3.19. glColorPointerEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glColorPointerEXT
Name
glColorPointerEXT - define a array of colors
C Specification
void glColorPointerEXT( GLint size,
GLenum type,
GLsizei stride,
GLsizei count,
const GLvoid *pointer )
Parameters
size Specifies the number of components per color. It must be 3 or 4.
type Specifies the data type of each color component in the array.
Symbolic constants GL_BYTE, GL_UNSIGNED_BYTE, GL_SHORT,
GL_UNSIGNED_SHORT, GL_INT, GL_UNSIGNED_INT, GL_FLOAT, or
GL_DOUBLE_EXT, are accepted.
stride Specifies the byte offset between consecutive colors. If stride
is zero the colors are understood to be tightly packed in the
array.
count Specifies the number of colors, counting from the first, that are
static.
pointer Specifies a pointer to the first component of the first color
element in the array.
Description
glColorPointerEXT specifies the location and data format of an array of
color components to use when rendering using the vertex array extension.
size specifies the number of components per color, and must be 3 or 4.
type specifies the data type of each color component and stride gives the
byte stride from one color to the next allowing vertexes and attributes to
be packed into a single array or stored in separate arrays. (Single-array
storage may be more efficient on some implementations.) count indicates
the number of array elements (counting from the first) that are static.
Static elements may be modified by the application, but once they are
modified, the application must explicitly respecify the array before using
it for any rendering. When a color array is specified, size, type, stride,
count and pointer are saved as client-side state, and static array elements
may be cached by the implementation.
The color array is enabled and disabled using glEnable and glDisable with
the argument GL_COLOR_ARRAY_EXT. If enabled, the color array is used when
glDrawArraysEXT or glArrayElementEXT is called.
Use glDrawArraysEXT to define a sequence of primitives (all of the same
type) from pre-specified vertex and vertex attribute arrays. Use
glArrayElementEXT to specify primitives by indexing vertexes and vertex
attributes.
Notes
Non-static array elements are not accessed until glArrayElementEXT or
glDrawArraysEXT is executed.
By default the color array is disabled and it won't be accessed when
glArrayElementEXT or glDrawArraysEXT is called.
Although it is not an error to call glColorPointerEXT between the
execution of glBegin and the corresponding execution of glEnd, the results
are undefined.
glColorPointerEXT will typically be implemented on the client side with no
protocol.
Since the color array parameters are client side state, they are not saved
or restored by glPushAttrib and glPopAttrib.
glColorPointerEXT commands are not entered into display lists.
glColorPointerEXT is part of the EXT_vertex_array extension, not
part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
Errors
GL_INVALID_VALUE is generated if size is not 3 or 4.
GL_INVALID_ENUM is generated if type is not an accepted value.
GL_INVALID_VALUE is generated if stride or count is negative.
Associated Gets
glIsEnabled with argument GL_COLOR_ARRAY_EXT
glGet with argument GL_COLOR_ARRAY_SIZE_EXT
glGet with argument GL_COLOR_ARRAY_TYPE_EXT
glGet with argument GL_COLOR_ARRAY_STRIDE_EXT
glGet with argument GL_COLOR_ARRAY_COUNT_EXT
glGetPointervEXT with argument GL_COLOR_ARRAY_POINTER_EXT
See Also
glArrayElementEXT, glDrawArraysEXT, glEdgeFlagPointerEXT, glGetPointervEXT,
glIndexPointerEXT, glNormalPointerEXT, glTexCoordPointerEXT,
glVertexPointerEXT, glEnable
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ΓòÉΓòÉΓòÉ 3.20. glCopyPixels ΓòÉΓòÉΓòÉ
OpenGL man pages
glCopyPixels
Name
glCopyPixels - copy pixels in the frame buffer
C Specification
void glCopyPixels( GLint x,
GLint y,
GLsizei width,
GLsizei height,
GLenum type )
Parameters
x, y Specify the window coordinates of the lower left corner of the
rectangular region of pixels to be copied.
width, height
Specify the dimensions of the rectangular region of pixels to be
copied. Both must be nonnegative.
type Specifies whether color values, depth values, or stencil values are to
be copied. Symbolic constants GL_COLOR, GL_DEPTH, and GL_STENCIL are
accepted.
Description
glCopyPixels copies a screen-aligned rectangle of pixels from the specified
frame buffer location to a region relative to the current raster position.
Its operation is well defined only if the entire pixel source region is
within the exposed portion of the window. Results of copies from outside
the window, or from regions of the window that are not exposed, are
hardware dependent and undefined.
x and y specify the window coordinates of the lower left corner of the
rectangular region to be copied. width and height specify the dimensions
of the rectangular region to be copied. Both width and height must not be
negative.
Several parameters control the processing of the pixel data while it is
being copied. These parameters are set with three commands:
glPixelTransfer, glPixelMap, and glPixelZoom. This reference page
describes the effects on glCopyPixels of most, but not all, of the
parameters specified by these three commands.
glCopyPixels copies values from each pixel with the lower left-hand corner
at (x + i, y + j) for 0<=i<width and 0<=j<height. This pixel is said to be
the ith pixel in the jth row. Pixels are copied in row order from the
lowest to the highest row, left to right in each row.
type specifies whether color, depth, or stencil data is to be copied. The
details of the transfer for each data type are as follows:
GL_COLOR Indices or RGBA colors are read from the buffer currently
specified as the read source buffer (see glReadBuffer). If
the GL is in color index mode, each index that is read from
this buffer is converted to a fixed-point format with an
unspecified number of bits to the right of the binary point.
Each index is then shifted left by GL_INDEX_SHIFT bits, and
added to GL_INDEX_OFFSET. If GL_INDEX_SHIFT is negative,
the shift is to the right. In either case, zero bits fill
otherwise unspecified bit locations in the result. If
GL_MAP_COLOR is true, the index is replaced with the value
that it references in lookup table GL_PIXEL_MAP_I_TO_I.
Whether the lookup replacement of the index is done or not,
b
the integer part of the index is then ANDed with 2 -1, where
b is the number of bits in a color index buffer.
If the GL is in RGBA mode, the red, green, blue, and alpha
components of each pixel that is read are converted to an
internal floating-point format with unspecified precision.
The conversion maps the largest representable component
value to 1.0, and component value zero to 0.0. The
resulting floating-point color values are then multiplied by
GL_c_SCALE and added to GL_c_BIAS, where c is RED, GREEN,
BLUE, and ALPHA for the respective color components. The
results are clamped to the range [0,1]. If GL_MAP_COLOR is
true, each color component is scaled by the size of lookup
table GL_PIXEL_MAP_c_TO_c, then replaced by the value that
it references in that table. c is R, G, B, or A,
respectively.
The resulting indices or RGBA colors are then converted to
fragments by attaching the current raster position z
coordinate and texture coordinates to each pixel, then
assigning window coordinates (x +i,y +j), where (x ,y ) is
r r r r
the current raster position, and the pixel was the ith pixel
in the jth row. These pixel fragments are then treated just
like the fragments generated by rasterizing points, lines,
or polygons. Texture mapping, fog, and all the fragment
operations are applied before the fragments are written to
the frame buffer.
GL_DEPTH Depth values are read from the depth buffer and converted
directly to an internal floating-point format with
unspecified precision. The resulting floating-point depth
value is then multiplied by GL_DEPTH_SCALE and added to
GL_DEPTH_BIAS. The result is clamped to the range [0,1].
The resulting depth components are then converted to
fragments by attaching the current raster position color or
color index and texture coordinates to each pixel, then
assigning window coordinates (x +i,y +j), where (x ,y ) is
r r r r
the current raster position, and the pixel was the ith pixel
in the jth row. These pixel fragments are then treated just
like the fragments generated by rasterizing points, lines,
or polygons. Texture mapping, fog, and all the fragment
operations are applied before the fragments are written to
the frame buffer.
GL_STENCIL Stencil indices are read from the stencil buffer and
converted to an internal fixed-point format with an
unspecified number of bits to the right of the binary point.
Each fixed-point index is then shifted left by
GL_INDEX_SHIFT bits, and added to GL_INDEX_OFFSET. If
GL_INDEX_SHIFT is negative, the shift is to the right. In
either case, zero bits fill otherwise unspecified bit
locations in the result. If GL_MAP_STENCIL is true, the
index is replaced with the value that it references in
lookup table GL_PIXEL_MAP_S_TO_S. Whether the lookup
replacement of the index is done or not, the integer part of
b
the index is then ANDed with 2 -1, where b is the number of
bits in the stencil buffer. The resulting stencil indices
are then written to the stencil buffer such that the index
read from the ith location of the jth row is written to
location (x +i,y +j), where (x ,y ) is the current raster
r r r r
position. Only the pixel ownership test, the scissor test,
and the stencil writemask affect these writes.
The rasterization described thus far assumes pixel zoom factors of 1.0. If
glPixelZoom is used to change the x and y pixel zoom factors, pixels are
converted to fragments as follows. If (x , y ) is the current raster
r r
position, and a given pixel is in the ith location in the jth row of the
source pixel rectangle, then fragments are generated for pixels whose
centers are in the rectangle with corners at
(x +zoom i, y +zoom j)
r x r y
and
(x +zoom (i+1), y +zoom (j+1))
r x r y
where zoom is the value of GL_ZOOM_X and zoom is the value of GL_ZOOM_Y.
x y
Examples
To copy the color pixel in the lower left corner of the window to the
current raster position, use glCopyPixels(0, 0, 1, 1, GL_COLOR);
Notes
Modes specified by glPixelStore have no effect on the operation of
glCopyPixels.
Errors
GL_INVALID_ENUM is generated if type is not an accepted value.
GL_INVALID_VALUE is generated if either width or height is negative.
GL_INVALID_OPERATION is generated if type is GL_DEPTH and there is no depth
buffer.
GL_INVALID_OPERATION is generated if type is GL_STENCIL and there is no
stencil buffer.
GL_INVALID_OPERATION is generated if glCopyPixels is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_CURRENT_RASTER_POSITION
glGet with argument GL_CURRENT_RASTER_POSITION_VALID
See Also
glDepthFunc, glDrawBuffer, glDrawPixels, glPixelMap, glPixelTransfer,
glPixelZoom, glRasterPos, glReadBuffer, glReadPixels, glStencilFunc
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ΓòÉΓòÉΓòÉ 3.21. glCullFace ΓòÉΓòÉΓòÉ
OpenGL man pages
glCullFace
Name
glCullFace - specify whether front- or back-facing facets can be culled
C Specification
void glCullFace( GLenum mode )
Parameters
mode Specifies whether front- or back-facing facets are candidates for
culling. Symbolic constants GL_FRONT, GL_BACK, and GL_FRONT_AND_BACK
are accepted. The default value is GL_BACK.
Description
glCullFace specifies whether front- or back-facing facets are culled (as
specified by mode) when facet culling is enabled. Facet culling is enabled
and disabled using the glEnable and glDisable commands with the argument
GL_CULL_FACE. Facets include triangles, quadrilaterals, polygons, and
rectangles.
glFrontFace specifies which of the clockwise and counterclockwise facets
are front-facing and back-facing. See glFrontFace.
Notes
If the mode is GL_FRONT_AND_BACK then no facets are drawn, but other
primitives such as points and lines are.
Errors
GL_INVALID_ENUM is generated if mode is not an accepted value.
GL_INVALID_OPERATION is generated if glCullFace is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glIsEnabled with argument GL_CULL_FACE
glGet with argument GL_CULL_FACE_MODE
See Also
glEnable, glFrontFace
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ΓòÉΓòÉΓòÉ 3.22. glDeleteLists ΓòÉΓòÉΓòÉ
OpenGL man pages
glDeleteLists
Name
glDeleteLists - delete a contiguous group of display lists
C Specification
void glDeleteLists( GLuint list,
GLsizei range )
Parameters
list Specifies the integer name of the first display list to delete.
range Specifies the number of display lists to delete.
Description
glDeleteLists causes a contiguous group of display lists to be deleted.
list is the name of the first display list to be deleted, and range is the
number of display lists to delete. All display lists d with list <= d <=
list + range - 1 are deleted.
All storage locations allocated to the specified display lists are freed,
and the names are available for reuse at a later time. Names within the
range that do not have an associated display list are ignored. If range is
zero, nothing happens.
Errors
GL_INVALID_VALUE is generated if range is negative.
GL_INVALID_OPERATION is generated if glDeleteLists is executed between the
execution of glBegin and the corresponding execution of glEnd.
See Also
glCallList, glCallLists, glGenLists, glIsList, glNewList
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ΓòÉΓòÉΓòÉ 3.23. glDepthFunc ΓòÉΓòÉΓòÉ
OpenGL man pages
glDepthFunc
Name
glDepthFunc - specify the value used for depth buffer comparisons
C Specification
void glDepthFunc( GLenum func )
Parameters
func Specifies the depth comparison function. Symbolic constants
GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL, GL_GREATER, GL_NOTEQUAL,
GL_GEQUAL, and GL_ALWAYS are accepted. The default value is GL_LESS.
Description
glDepthFunc specifies the function used to compare each incoming pixel z
value with the z value present in the depth buffer. The comparison is
performed only if depth testing is enabled. (See glEnable and glDisable of
GL_DEPTH_TEST.)
func specifies the conditions under which the pixel will be drawn. The
comparison functions are as follows:
GL_NEVER Never passes.
GL_LESS Passes if the incoming z value is less than the stored
z value.
GL_EQUAL Passes if the incoming z value is equal to the stored z
value.
GL_LEQUAL Passes if the incoming z value is less than or equal to
the stored z value.
GL_GREATER Passes if the incoming z value is greater than the
stored z value.
GL_NOTEQUAL Passes if the incoming z value is not equal to the
stored z value.
GL_GEQUAL Passes if the incoming z value is greater than or equal
to the stored z value.
GL_ALWAYS Always passes.
The default value of func is GL_LESS. Initially, depth testing is
disabled.
Errors
GL_INVALID_ENUM is generated if func is not an accepted value.
GL_INVALID_OPERATION is generated if glDepthFunc is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_DEPTH_FUNC
glIsEnabled with argument GL_DEPTH_TEST
See Also
glDepthRange, glEnable
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ΓòÉΓòÉΓòÉ 3.24. glDepthMask ΓòÉΓòÉΓòÉ
OpenGL man pages
glDepthMask
Name
glDepthMask - enable or disable writing into the depth buffer
C Specification
void glDepthMask( GLboolean flag )
Parameters
flag Specifies whether the depth buffer is enabled for writing. If flag
is zero, depth buffer writing is disabled. Otherwise, it is enabled.
Initially, depth buffer writing is enabled.
Description
glDepthMask specifies whether the depth buffer is enabled for writing. If
flag is zero, depth buffer writing is disabled. Otherwise, it is enabled.
Initially, depth buffer writing is enabled.
Errors
GL_INVALID_OPERATION is generated if glDepthMask is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_DEPTH_WRITEMASK
See Also
glColorMask, glDepthFunc, glDepthRange, glIndexMask, glStencilMask
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ΓòÉΓòÉΓòÉ 3.25. glDepthRange ΓòÉΓòÉΓòÉ
OpenGL man pages
glDepthRange
Name
glDepthRange - specify the mapping of z values from normalized device
coordinates to window coordinates
C Specification
void glDepthRange( GLclampd near,
GLclampd far )
Parameters
near Specifies the mapping of the near clipping plane to window
coordinates. The default value is 0.
far Specifies the mapping of the far clipping plane to window
coordinates. The default value is 1.
Description
After clipping and division by w, z coordinates range from -1.0 to 1.0,
corresponding to the near and far clipping planes. glDepthRange specifies
a linear mapping of the normalized z coordinates in this range to window z
coordinates. Regardless of the actual depth buffer implementation, window
coordinate depth values are treated as though they range from 0.0 through
1.0 (like color components). Thus, the values accepted by glDepthRange are
both clamped to this range before they are accepted.
The default mapping of 0,1 maps the near plane to 0 and the far plane to 1.
With this mapping, the depth buffer range is fully utilized.
Notes
It is not necessary that near be less than far. Reverse mappings such as
1,0 are acceptable.
Errors
GL_INVALID_OPERATION is generated if glDepthRange is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_DEPTH_RANGE
See Also
glDepthFunc, glViewport
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ΓòÉΓòÉΓòÉ 3.26. glDrawArraysEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glDrawArraysEXT
Name
glDrawArraysEXT - render primitives from array data
C Specification
void glDrawArraysEXT( GLenum mode,
GLint first,
GLsizei count )
Parameters
mode Specifies what kind of primitives to render. Symbolic constants
GL_POINTS, GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES, GL_TRIANGLE_STRIP,
GL_TRIANGLE_FAN, GL_TRIANGLES, GL_QUAD_STRIP, GL_QUADS, and
GL_POLYGON are accepted.
first Specifies the starting index in the enabled arrays.
count Specifies the number of indices which should be rendered.
Description
glDrawArraysEXT makes it possible to specify multiple geometric primitives
with very few subroutine calls. Instead of calling an OpenGL procedure to
pass each individual vertex, normal, or color, separate arrays of vertexes,
normals, and colors can be prespecified, and used to define a sequence of
primitives (all of the same type) with a single call to glDrawArraysEXT.
When glDrawArraysEXT is called, count sequential elements from each enabled
array are used to construct a sequence of geometric primitives, beginning
with element first. mode specifies what kind of primitives are constructed,
and how the array elements are used to construct these primitives. If
GL_VERTEX_ARRAY_EXT is not enabled, no geometric primitives are generated.
Vertex attributes that are modified by glDrawArraysEXT have an unspecified
value after glDrawArraysEXT returns. For example, if GL_COLOR_ARRAY_EXT is
enabled, the value of the current color is undefined after glDrawArraysEXT
executes. Attributes that aren't modified remain well defined.
Operation of glDrawArraysEXT is atomic with respect to error generation.
If an error is generated, no other operations take place.
Notes
glDrawArraysEXT may be included in display lists. If glDrawArraysEXT is
entered into a display list, the necessary array data (determined by the
array pointers and enables) is also entered into the display list. Because
the array pointers and enables are client side state, their values affect
display lists when the lists are created, not when the lists are executed.
Static array data may be read and cached by the implementation at any time.
If static array elements are modified and the arrays are not respecified,
the results of any subsequent calls to glDrawArraysEXT are undefined.
Although it is not an error to respecify an array between the execution of
glBegin and the corresponding execution of glEnd, the result of such
respecification is undefined.
glDrawArraysEXT is part of the EXT_vertex_array extension, not
part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
Errors
GL_INVALID_ENUM is generated if mode is not an accepted value.
GL_INVALID_VALUE is generated if count is negative.
GL_INVALID_OPERATION is generated if glDrawArraysEXT is called between the
execution of glBegin and the corresponding execution of glEnd.
See Also
glArrayElementEXT, glColorPointerEXT, glEdgeFlagPointerEXT,
glGetPointervEXT, glIndexPointerEXT, glNormalPointerEXT,
glTexCoordPointerEXT, glVertexPointerEXT
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ΓòÉΓòÉΓòÉ 3.27. glDrawBuffer ΓòÉΓòÉΓòÉ
OpenGL man pages
glDrawBuffer
Name
glDrawBuffer - specify which color buffers are to be drawn into
C Specification
void glDrawBuffer( GLenum mode )
Parameters
mode Specifies up to four color buffers to be drawn into. Symbolic
constants GL_NONE, GL_FRONT_LEFT, GL_FRONT_RIGHT, GL_BACK_LEFT,
GL_BACK_RIGHT, GL_FRONT, GL_BACK, GL_LEFT, GL_RIGHT,
GL_FRONT_AND_BACK, and GL_AUXi, where i is between 0 and
``GL_AUX_BUFFERS'' -1, are accepted (GL_AUX_BUFFERS is not the upper
limit; use glGet to query the number of available aux buffers.) The
default value is GL_FRONT for single-buffered contexts, and GL_BACK
for double-buffered contexts.
Description
When colors are written to the frame buffer, they are written into the
color buffers specified by glDrawBuffer. The specifications are as
follows:
GL_NONE No color buffers are written.
GL_FRONT_LEFT Only the front left color buffer is written.
GL_FRONT_RIGHT Only the front right color buffer is written.
GL_BACK_LEFT Only the back left color buffer is written.
GL_BACK_RIGHT Only the back right color buffer is written.
GL_FRONT Only the front left and front right color buffers
are written. If there is no front right color
buffer, only the front left color buffer is
written.
GL_BACK Only the back left and back right color buffers
are written. If there is no back right color
buffer, only the back left color buffer is
written.
GL_LEFT Only the front left and back left color buffers
are written. If there is no back left color
buffer, only the front left color buffer is
written.
GL_RIGHT Only the front right and back right color buffers
are written. If there is no back right color
buffer, only the front right color buffer is
written.
GL_FRONT_AND_BACK All the front and back color buffers (front left,
front right, back left, back right) are written.
If there are no back color buffers, only the front
left and front right color buffers are written.
If there are no right color buffers, only the
front left and back left color buffers are
written. If there are no right or back color
buffers, only the front left color buffer is
written.
GL_AUXi Only auxiliary color buffer i is written.
If more than one color buffer is selected for drawing, then blending or
logical operations are computed and applied independently for each color
buffer and can produce different results in each buffer.
Monoscopic contexts include only left buffers, and stereoscopic contexts
include both left and right buffers. Likewise, single-buffered contexts
include only front buffers, and double-buffered contexts include both front
and back buffers. The context is selected at GL initialization.
Notes
It is always the case that GL_AUXi = GL_AUX0 + i.
Errors
GL_INVALID_ENUM is generated if mode is not an accepted value.
GL_INVALID_OPERATION is generated if none of the buffers indicated by mode
exists.
GL_INVALID_OPERATION is generated if glDrawBuffer is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_DRAW_BUFFER
glGet with argument GL_AUX_BUFFERS
See Also
glBlendFunc, glColorMask, glIndexMask, glLogicOp, glReadBuffer
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ΓòÉΓòÉΓòÉ 3.28. glDrawPixels ΓòÉΓòÉΓòÉ
OpenGL man pages
glDrawPixels
Name
glDrawPixels - write a block of pixels to the frame buffer
C Specification
void glDrawPixels( GLsizei width,
GLsizei height,
GLenum format,
GLenum type,
const GLvoid *pixels )
Parameters
width, height Specify the dimensions of the pixel rectangle that will be
written into the frame buffer.
format Specifies the format of the pixel data. Symbolic constants
GL_COLOR_INDEX, GL_STENCIL_INDEX, GL_DEPTH_COMPONENT,
GL_RGBA, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB,
GL_LUMINANCE, and GL_LUMINANCE_ALPHA are accepted.
type Specifies the data type for pixels. Symbolic constants
GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,
GL_SHORT, GL_UNSIGNED_INT, GL_INT, and GL_FLOAT are accepted.
pixels Specifies a pointer to the pixel data.
Description
glDrawPixels reads pixel data from memory and writes it into the frame
buffer relative to the current raster position. Use glRasterPos to set the
current raster position, and use glGet with argument
GL_CURRENT_RASTER_POSITION to query the raster position.
Several parameters define the encoding of pixel data in memory and control
the processing of the pixel data before it is placed in the frame buffer.
These parameters are set with four commands: glPixelStore, glPixelTransfer,
glPixelMap, and glPixelZoom. This reference page describes the effects on
glDrawPixels of many, but not all, of the parameters specified by these
four commands.
Data is read from pixels as a sequence of signed or unsigned bytes, signed
or unsigned shorts, signed or unsigned integers, or single-precision
floating-point values, depending on type. Each of these bytes, shorts,
integers, or floating-point values is interpreted as one color or depth
component, or one index, depending on format. Indices are always treated
individually. Color components are treated as groups of one, two, three,
or four values, again based on format. Both individual indices and groups
of components are referred to as pixels. If type is GL_BITMAP, the data
must be unsigned bytes, and format must be either GL_COLOR_INDEX or
GL_STENCIL_INDEX. Each unsigned byte is treated as eight 1-bit pixels,
with bit ordering determined by GL_UNPACK_LSB_FIRST (see glPixelStore).
widthxheight pixels are read from memory, starting at location pixels. By
default, these pixels are taken from adjacent memory locations, except that
after all width pixels are read, the read pointer is advanced to the next
four-byte boundary. The four-byte row alignment is specified by
glPixelStore with argument GL_UNPACK_ALIGNMENT, and it can be set to one,
two, four, or eight bytes. Other pixel store parameters specify different
read pointer advancements, both before the first pixel is read, and after
all width pixels are read. Refer to the glPixelStore reference page for
details on these options.
The widthxheight pixels that are read from memory are each operated on in
the same way, based on the values of several parameters specified by
glPixelTransfer and glPixelMap. The details of these operations, as well
as the target buffer into which the pixels are drawn, are specific to the
format of the pixels, as specified by format. format can assume one of
eleven symbolic values:
GL_COLOR_INDEX
Each pixel is a single value, a color index. It is converted to
fixed-point format, with an unspecified number of bits to the
right of the binary point, regardless of the memory data type.
Floating-point values convert to true fixed-point values. Signed
and unsigned integer data is converted with all fraction bits set
to zero. Bitmap data convert to either 0.0 or 1.0.
Each fixed-point index is then shifted left by GL_INDEX_SHIFT
bits and added to GL_INDEX_OFFSET. If GL_INDEX_SHIFT is
negative, the shift is to the right. In either case, zero bits
fill otherwise unspecified bit locations in the result.
If the GL is in RGBA mode, the resulting index is converted to an
RGBA pixel using the GL_PIXEL_MAP_I_TO_R, GL_PIXEL_MAP_I_TO_G,
GL_PIXEL_MAP_I_TO_B, and GL_PIXEL_MAP_I_TO_A tables. If the GL
is in color index mode, and if GL_MAP_COLOR is true, the index is
replaced with the value that it references in lookup table
GL_PIXEL_MAP_I_TO_I. Whether the lookup replacement of the index
is done or not, the integer part of the index is then ANDed with
b
2 -1, where b is the number of bits in a color index buffer.
The resulting indices or RGBA colors are then converted to
fragments by attaching the current raster position z coordinate
and texture coordinates to each pixel, then assigning x and y
window coordinates to the nth fragment such that
x = x + n mod width
n r
y = y + floor (n/width)
n r
where (x ,y ) is the current raster position. These pixel
r r
fragments are then treated just like the fragments generated by
rasterizing points, lines, or polygons. Texture mapping, fog,
and all the fragment operations are applied before the fragments
are written to the frame buffer.
GL_STENCIL_INDEX
Each pixel is a single value, a stencil index. It is converted
to fixed-point format, with an unspecified number of bits to the
right of the binary point, regardless of the memory data type.
Floating-point values convert to true fixed-point values. Signed
and unsigned integer data is converted with all fraction bits set
to zero. Bitmap data convert to either 0.0 or 1.0.
Each fixed-point index is then shifted left by GL_INDEX_SHIFT
bits, and added to GL_INDEX_OFFSET. If GL_INDEX_SHIFT is
negative, the shift is to the right. In either case, zero bits
fill otherwise unspecified bit locations in the result. If
GL_MAP_STENCIL is true, the index is replaced with the value that
it references in lookup table GL_PIXEL_MAP_S_TO_S. Whether the
lookup replacement of the index is done or not, the integer part
b
of the index is then ANDed with 2 -1, where b is the number of
bits in the stencil buffer. The resulting stencil indices are
then written to the stencil buffer such that the nth index is
written to location
x = x + n mod width
n r
y = y + floor (n/width)
n r
where (x ,y ) is the current raster position. Only the pixel
r r
ownership test, the scissor test, and the stencil writemask affect
these writes.
GL_DEPTH_COMPONENT
Each pixel is a single-depth component. Floating-point data is
converted directly to an internal floating-point format with
unspecified precision. Signed integer data is mapped linearly to the
internal floating-point format such that the most positive
representable integer value maps to 1.0, and the most negative
representable value maps to -1.0. Unsigned integer data is mapped
similarly: the largest integer value maps to 1.0, and zero maps to
0.0. The resulting floating-point depth value is then multiplied by
GL_DEPTH_SCALE and added to GL_DEPTH_BIAS. The result is clamped to
the range [0,1].
The resulting depth components are then converted to fragments by
attaching the current raster position color or color index and texture
coordinates to each pixel, then assigning x and y window coordinates
to the nth fragment such that
x = x + n mod width
n r
y = y + floor (n/width)
n r
where (x ,y ) is the current raster position. These pixel fragments
r r
are then treated just like the fragments generated by rasterizing
points, lines, or polygons. Texture mapping, fog, and all the
fragment operations are applied before the fragments are written to
the frame buffer.
GL_RGBA
Each pixel is a four-component group: red first, followed by green,
followed by blue, followed by alpha. Floating-point values are
converted directly to an internal floating-point format with
unspecified precision. Signed integer values are mapped linearly to
the internal floating-point format such that the most positive
representable integer value maps to 1.0, and the most negative
representable value maps to -1.0. Unsigned integer data is mapped
similarly: the largest integer value maps to 1.0, and zero maps to
0.0. The resulting floating-point color values are then multiplied by
GL_c_SCALE and added to GL_c_BIAS, where c is RED, GREEN, BLUE, and
ALPHA for the respective color components. The results are clamped to
the range [0,1].
If GL_MAP_COLOR is true, each color component is scaled by the size of
lookup table GL_PIXEL_MAP_c_TO_c, then replaced by the value that it
references in that table. c is R, G, B, or A, respectively.
The resulting RGBA colors are then converted to fragments by attaching
the current raster position z coordinate and texture coordinates to
each pixel, then assigning x and y window coordinates to the nth
fragment such that
x = x + n mod width
n r
y = y + floor (n/width)
n r
where (x ,y ) is the current raster position. These pixel fragments
r r
are then treated just like the fragments generated by rasterizing
points, lines, or polygons. Texture mapping, fog, and all the
fragment operations are applied before the fragments are written to
the frame buffer.
GL_RED
Each pixel is a single red component. This component is converted to
the internal floating-point format in the same way as the red
component of an RGBA pixel is, then it is converted to an RGBA pixel
with green and blue set to 0.0, and alpha set to 1.0. After this
conversion, the pixel is treated just as if it had been read as an
RGBA pixel.
GL_GREEN
Each pixel is a single green component. This component is converted
to the internal floating-point format in the same way as the green
component of an RGBA pixel is, then it is converted to an RGBA pixel
with red and blue set to 0.0, and alpha set to 1.0. After this
conversion, the pixel is treated just as if it had been read as an
RGBA pixel.
GL_BLUE
Each pixel is a single blue component. This component is converted to
the internal floating-point format in the same way as the blue
component of an RGBA pixel is, then it is converted to an RGBA pixel
with red and green set to 0.0, and alpha set to 1.0. After this
conversion, the pixel is treated just as if it had been read as an
RGBA pixel.
GL_ALPHA
Each pixel is a single alpha component. This component is converted
to the internal floating-point format in the same way as the alpha
component of an RGBA pixel is, then it is converted to an RGBA pixel
with red, green, and blue set to 0.0. After this conversion, the
pixel is treated just as if it had been read as an RGBA pixel.
GL_RGB
Each pixel is a three-component group: red first, followed by green,
followed by blue. Each component is converted to the internal
floating-point format in the same way as the red, green, and blue
components of an RGBA pixel are. The color triple is converted to an
RGBA pixel with alpha set to 1.0. After this conversion, the pixel is
treated just as if it had been read as an RGBA pixel.
GL_LUMINANCE
Each pixel is a single luminance component. This component is
converted to the internal floating-point format in the same way as the
red component of an RGBA pixel is, then it is converted to an RGBA
pixel with red, green, and blue set to the converted luminance value,
and alpha set to 1.0. After this conversion, the pixel is treated
just as if it had been read as an RGBA pixel.
GL_LUMINANCE_ALPHA
Each pixel is a two-component group: luminance first, followed by
alpha. The two components are converted to the internal floating-
point format in the same way as the red component of an RGBA pixel is,
then they are converted to an RGBA pixel with red, green, and blue set
to the converted luminance value, and alpha set to the converted alpha
value. After this conversion, the pixel is treated just as if it had
been read as an RGBA pixel.
The following table summarizes the meaning of the valid constants for the
type parameter:
-------------------------------------------------------------
| type | corresponding type |
-------------------------------------------------------------
|GL_UNSIGNED_BYTE | unsigned 8-bit integer |
| GL_BYTE | signed 8-bit integer |
| GL_BITMAP | single bits in unsigned 8-bit integers |
|GL_UNSIGNED_SHORT | unsigned 16-bit integer |
| GL_SHORT | signed 16-bit integer |
| GL_UNSIGNED_INT | unsigned 32-bit integer |
| GL_INT | 32-bit integer |
| GL_FLOAT | single-precision floating-point |
-------------------------------------------------------------
The rasterization described thus far assumes pixel zoom factors of 1.0. If
glPixelZoom is used to change the x and y pixel zoom factors, pixels are
converted to fragments as follows. If (x , y ) is the current raster
r r
position, and a given pixel is in the nth column and mth row of the pixel
rectangle, then fragments are generated for pixels whose centers are in the
rectangle with corners at
(x + zoom n, y + zoom m)
r x r y
(x + zoom (n+1), y + zoom (m+1))
r x r y
where zoom is the value of GL_ZOOM_X and zoom is the value of GL_ZOOM_Y.
x y
Errors
GL_INVALID_VALUE is generated if either width or height is negative.
GL_INVALID_ENUM is generated if format or type is not one of the accepted
values.
GL_INVALID_OPERATION is generated if format is GL_RED, GL_GREEN, GL_BLUE,
GL_ALPHA, GL_RGB, GL_RGBA, GL_LUMINANCE, or GL_LUMINANCE_ALPHA, and the GL
is in color index mode.
GL_INVALID_ENUM is generated if type is GL_BITMAP and format is not either
GL_COLOR_INDEX or GL_STENCIL_INDEX.
GL_INVALID_OPERATION is generated if format is GL_STENCIL_INDEX and there
is no stencil buffer.
GL_INVALID_OPERATION is generated if glDrawPixels is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_CURRENT_RASTER_POSITION
glGet with argument GL_CURRENT_RASTER_POSITION_VALID
See Also
glAlphaFunc, glBlendFunc, glCopyPixels, glDepthFunc, glLogicOp, glPixelMap,
glPixelStore, glPixelTransfer, glPixelZoom, glRasterPos, glReadPixels,
glScissor, glStencilFunc
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ΓòÉΓòÉΓòÉ 3.29. glEdgeFlag ΓòÉΓòÉΓòÉ
OpenGL man pages
glEdgeFlag
Name
glEdgeFlag, glEdgeFlagv - flag edges as either boundary or nonboundary
C Specification
void glEdgeFlag( GLboolean flag )
Parameters
flag Specifies the current edge flag value, either true or false.
C Specification
void glEdgeFlagv( const GLboolean *flag )
Parameters
flag Specifies a pointer to an array that contains a single Boolean
element, which replaces the current edge flag value.
Description
Each vertex of a polygon, separate triangle, or separate quadrilateral
specified between a glBegin/glEnd pair is marked as the start of either a
boundary or nonboundary edge. If the current edge flag is true when the
vertex is specified, the vertex is marked as the start of a boundary edge.
Otherwise, the vertex is marked as the start of a nonboundary edge.
glEdgeFlag sets the edge flag to true if flag is nonzero, false otherwise.
The vertices of connected triangles and connected quadrilaterals are always
marked as boundary, regardless of the value of the edge flag.
Boundary and nonboundary edge flags on vertices are significant only if
GL_POLYGON_MODE is set to GL_POINT or GL_LINE. See glPolygonMode.
Initially, the edge flag bit is true.
Notes
The current edge flag can be updated at any time. In particular,
glEdgeFlag can be called between a call to glBegin and the corresponding
call to glEnd.
Associated Gets
glGet with argument GL_EDGE_FLAG
See Also
glBegin, glPolygonMode
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ΓòÉΓòÉΓòÉ 3.30. glEdgeFlagPointerEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glEdgeFlagPointerEXT
Name
glEdgeFlagPointerEXT - define an array of edge flags
C Specification
void glEdgeFlagPointerEXT( GLsizei stride,
GLsizei count,
const GLboolean *pointer )
Parameters
stride Specifies the byte offset between consecutive edge flags. If
stride is zero the edge flags are understood to be tightly packed
in the array.
count Specifies the number of edge flags, counting from the first, that
are static.
pointer Specifies a pointer to the first edge flag in the array.
Description
glEdgeFlagPointerEXT specifies the location and data format of an array of
boolean edge flags to use when rendering when using the vertex array
extension. stride gives the byte stride from one edge flag to the next
allowing vertexes and attributes to be packed into a single array or stored
in separate arrays. (Single-array storage may be more efficient on some
implementations.) count indicates the number of array elements (counting
from the first) that are static. Static elements may be modified by the
application, but once they are modified, the application must explicitly
respecify the array before using it for any rendering. When an edge flag
array is specified, stride, count and pointer are saved as client-side state,
and static array elements may be cached by the implementation.
The edge flag array is enabled and disabled using glEnable and glDisable
with the argument GL_EDGE_FLAG_ARRAY_EXT. If enabled, the edge flag array
is used when glDrawArraysEXT or glArrayElementEXT is called.
Use glDrawArraysEXT to define a sequence of primitives (all of the same
type) from pre-specified vertex and vertex attribute arrays. Use
glArrayElementEXT to specify primitives by indexing vertexes and vertex
attributes.
Notes
Non-static array elements are not accessed until glArrayElementEXT or
glDrawArraysEXT is executed.
By default the edge flag array is disabled and it won't be accessed when
glArrayElementEXT or glDrawArraysEXT is called.
Although it is not an error to call glEdgeFlagPointerEXT between the
execution of glBegin and the corresponding execution of glEnd, the results
are undefined.
glEdgeFlagPointerEXT will typically be implemented on the client side with
no protocol.
Since the edge flag array parameters are client side state, they are not
saved or restored by glPushAttrib and glPopAttrib.
glEdgeFlagPointerEXT commands are not entered into display lists.
glEdgeFlagPointerEXT is part of the EXT_vertex_array extension,
not part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
Errors
GL_INVALID_ENUM is generated if stride or count is negative.
Associated Gets
glIsEnabled with argument GL_EDGE_FLAG_ARRAY_EXT
glGet with argument GL_EDGE_FLAG_ARRAY_STRIDE_EXT
glGet with argument GL_EDGE_FLAG_ARRAY_COUNT_EXT
glGetPointervEXT with argument GL_EDGE_FLAG_ARRAY_POINTER_EXT
See Also
glArrayElementEXT, glColorPointerEXT, glDrawArraysEXT, glGetPointervEXT,
glIndexPointerEXT, glNormalPointerEXT, glTexCoordPointerEXT,
glVertexPointerEXT, glEnable
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ΓòÉΓòÉΓòÉ 3.31. glEnable ΓòÉΓòÉΓòÉ
OpenGL man pages
glEnable
Name
glEnable, glDisable - enable or disable GL capabilities
C Specification
void glEnable( GLenum cap )
Parameters
cap Specifies a symbolic constant indicating a GL capability.
C Specification
void glDisable( GLenum cap )
Parameters
cap Specifies a symbolic constant indicating a GL capability.
Description
glEnable and glDisable enable and disable various capabilities. Use
glIsEnabled or glGet to determine the current setting of any capability.
Both glEnable and glDisable take a single argument, cap, which can assume
one of the following values:
GL_ALPHA_TEST If enabled, do alpha testing. See glAlphaFunc.
GL_AUTO_NORMAL If enabled, compute surface normal vectors
analytically when either GL_MAP2_VERTEX_3 or
GL_MAP2_VERTEX_4 is used to generate vertices.
See glMap2.
GL_BLEND If enabled, blend the incoming RGBA color values
with the values in the color buffers. See
glBlendFunc.
GL_CLIP_PLANEi If enabled, clip geometry against user-defined
clipping plane i. See glClipPlane.
GL_COLOR_ARRAY_EXT If enabled, colors are taken from the color array
when glArrayElementEXT or glDrawArraysEXT is
called. See glColorPointerEXT, glArrayElementEXT
and glDrawArraysEXT.
GL_COLOR_MATERIAL If enabled, have one or more material parameters
track the current color. See glColorMaterial.
GL_CULL_FACE If enabled, cull polygons based on their winding
in window coordinates. See glCullFace.
GL_DEPTH_TEST If enabled, do depth comparisons and update the
depth buffer. See glDepthFunc and glDepthRange.
GL_DITHER If enabled, dither color components or indices
before they are written to the color buffer.
GL_EDGE_FLAG_ARRAY_EXT If enabled, edge flags are taken from the edge
flags array when glArrayElementEXT or
glDrawArraysEXT is called. See
glEdgeFlagPointerEXT, glArrayElementEXT and
glDrawArraysEXT.
GL_FOG If enabled, blend a fog color into the
posttexturing color. See glFog.
GL_INDEX_ARRAY_EXT If enabled, color indexes are taken from the color
index array when glArrayElementEXT or
glDrawArraysEXT is called. See glIndexPointerEXT,
glArrayElementEXT and glDrawArraysEXT.
GL_LIGHTi If enabled, include light i in the evaluation of
the lighting equation. See glLightModel and
glLight.
GL_LIGHTING If enabled, use the current lighting parameters to
compute the vertex color or index. Otherwise,
simply associate the current color or index with
each vertex. See glMaterial, glLightModel, and
glLight.
GL_LINE_SMOOTH If enabled, draw lines with correct filtering.
Otherwise, draw aliased lines. See glLineWidth.
GL_LINE_STIPPLE If enabled, use the current line stipple pattern
when drawing lines. See glLineStipple.
GL_LOGIC_OP If enabled, apply the currently selected logical
operation to the incoming and color buffer
indices. See glLogicOp.
GL_MAP1_COLOR_4 If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate RGBA values. See
glMap1.
GL_MAP1_INDEX If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate color indices. See
glMap1.
GL_MAP1_NORMAL If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate normals. See
glMap1.
GL_MAP1_TEXTURE_COORD_1 If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate s texture
coordinates. See glMap1.
GL_MAP1_TEXTURE_COORD_2 If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate s and t texture
coordinates. See glMap1.
GL_MAP1_TEXTURE_COORD_3 If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate s, t, and r texture
coordinates. See glMap1.
GL_MAP1_TEXTURE_COORD_4 If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate s, t, r, and q
texture coordinates. See glMap1.
GL_MAP1_VERTEX_3 If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate will generate x, y,
and z vertex coordinates. See glMap1.
GL_MAP1_VERTEX_4 If enabled, calls to glEvalCoord1, glEvalMesh1,
and glEvalPoint1 will generate homogeneous x, y,
z, and w vertex coordinates. See glMap1.
GL_MAP2_COLOR_4 If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate RGBA values. See
glMap2.
GL_MAP2_INDEX If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate color indices. See
glMap2.
GL_MAP2_NORMAL If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate normals. See
glMap2.
GL_MAP2_TEXTURE_COORD_1 If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate s texture
coordinates. See glMap2.
GL_MAP2_TEXTURE_COORD_2 If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate s and t texture
coordinates. See glMap2.
GL_MAP2_TEXTURE_COORD_3 If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate s, t, and r texture
coordinates. See glMap2.
GL_MAP2_TEXTURE_COORD_4 If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate s, t, r, and q
texture coordinates. See glMap2.
GL_MAP2_VERTEX_3 If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate will generate x, y,
and z vertex coordinates. See glMap2.
GL_MAP2_VERTEX_4 If enabled, calls to glEvalCoord2, glEvalMesh2,
and glEvalPoint2 will generate homogeneous x, y,
z, and w vertex coordinates. See glMap2.
GL_NORMAL_ARRAY_EXT If enabled, normals are taken from the normal
array when glArrayElementEXT or glDrawArraysEXT is
called. See glNormalPointerEXT, glArrayElementEXT
and glDrawArraysEXT.
GL_NORMALIZE If enabled, normal vectors specified with glNormal
are scaled to unit length after transformation.
See glNormal.
GL_POINT_SMOOTH If enabled, draw points with proper filtering.
Otherwise, draw aliased points. See glPointSize.
GL_POLYGON_SMOOTH If enabled, draw polygons with proper filtering.
Otherwise, draw aliased polygons. See
glPolygonMode.
GL_POLYGON_STIPPLE If enabled, use the current polygon stipple
pattern when rendering polygons. See
glPolygonStipple.
GL_SCISSOR_TEST If enabled, discard fragments that are outside the
scissor rectangle. See glScissor.
GL_STENCIL_TEST If enabled, do stencil testing and update the
stencil buffer. See glStencilFunc and
glStencilOp.
GL_TEXTURE_1D If enabled, one-dimensional texturing is performed
(unless two-dimensional texturing is also
enabled). See glTexImage1D.
GL_TEXTURE_2D If enabled, two-dimensional texturing is
performed. See glTexImage2D.
GL_TEXTURE_COORD_ARRAY_EXT
If enabled, texture coordinates are taken from the
texture coordinates array when glArrayElementEXT
or glDrawArraysEXT is called. See
glTexCoordPointerEXT, glArrayElementEXT and
glDrawArraysEXT.
GL_TEXTURE_GEN_Q If enabled, the q texture coordinate is computed
using the texture generation function defined with
glTexGen. Otherwise, the current q texture
coordinate is used. See glTexGen.
GL_TEXTURE_GEN_R If enabled, the r texture coordinate is computed
using the texture generation function defined with
glTexGen. Otherwise, the current r texture
coordinate is used. See glTexGen.
GL_TEXTURE_GEN_S If enabled, the s texture coordinate is computed
using the texture generation function defined with
glTexGen. Otherwise, the current s texture
coordinate is used. See glTexGen.
GL_TEXTURE_GEN_T If enabled, the t texture coordinate is computed
using the texture generation function defined with
glTexGen. Otherwise, the current t texture
coordinate is used. See glTexGen.
GL_VERTEX_ARRAY_EXT If enabled, vertexes are taken from the vertex
array when glArrayElementEXT or glDrawArraysEXT is
called. See glVertexPointerEXT, glArrayElementEXT
and glDrawArraysEXT.
Errors
GL_INVALID_ENUM is generated if cap is not one of the values listed above.
GL_INVALID_OPERATION is generated if glEnable or glDisable is executed
between the execution of glBegin and the corresponding execution of glEnd.
See Also
glAlphaFunc, glBlendFunc, glClipPlane, glColorMaterial, glCullFace,
glDepthFunc, glDepthRange, glFog, glGet, glIsEnabled, glLight,
glLightModel, glLineWidth, glLineStipple, glLogicOp, glMap1, glMap2,
glMaterial, glNormal, glPointSize, glPolygonMode, glPolygonStipple,
glScissor, glStencilFunc, glStencilOp, glTexGen, glTexImage1D, glTexImage2D
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ΓòÉΓòÉΓòÉ 3.32. glEvalCoord ΓòÉΓòÉΓòÉ
OpenGL man pages
glEvalCoord
Name
glEvalCoord1d, glEvalCoord1f, glEvalCoord2d, glEvalCoord2f, glEvalCoord1dv,
glEvalCoord1fv, glEvalCoord2dv, glEvalCoord2fv - evaluate enabled one- and
two-dimensional maps
C Specification
void glEvalCoord1d( GLdouble u )
void glEvalCoord1f( GLfloat u )
void glEvalCoord2d( GLdouble u,
GLdouble v )
void glEvalCoord2f( GLfloat u,
GLfloat v )
Parameters
u Specifies a value that is the domain coordinate u to the basis function
defined in a previous glMap1 or glMap2 command.
v Specifies a value that is the domain coordinate v to the basis function
defined in a previous glMap2 command. This argument is not present in
an glEvalCoord1 command.
C Specification
void glEvalCoord1dv( const GLdouble *u )
void glEvalCoord1fv( const GLfloat *u )
void glEvalCoord2dv( const GLdouble *u )
void glEvalCoord2fv( const GLfloat *u )
Parameters
u Specifies a pointer to an array containing either one or two domain
coordinates. The first coordinate is u. The second coordinate is v,
which is present only in glEvalCoord2 versions.
Description
glEvalCoord1 evaluates enabled one-dimensional maps at argument u.
glEvalCoord2 does the same for two-dimensional maps using two domain
values, u and v. Maps are defined with glMap1 and glMap2 and enabled and
disabled with glEnable and glDisable.
When one of the glEvalCoord commands is issued, all currently enabled maps
of the indicated dimension are evaluated. Then, for each enabled map, it
is as if the corresponding GL command was issued with the computed value.
That is, if GL_MAP1_INDEX or GL_MAP2_INDEX is enabled, a glIndex command is
simulated. If GL_MAP1_COLOR_4 or GL_MAP2_COLOR_4 is enabled, a glColor
command is simulated. If GL_MAP1_NORMAL or GL_MAP2_NORMAL is enabled, a
normal vector is produced, and if any of GL_MAP1_TEXTURE_COORD_1,
GL_MAP1_TEXTURE_COORD_2, GL_MAP1_TEXTURE_COORD_3, GL_MAP1_TEXTURE_COORD_4,
GL_MAP2_TEXTURE_COORD_1, GL_MAP2_TEXTURE_COORD_2, GL_MAP2_TEXTURE_COORD_3,
or GL_MAP2_TEXTURE_COORD_4 is enabled, then an appropriate glTexCoord
command is simulated.
The GL uses evaluated values instead of current values for those
evaluations that are enabled, and current values otherwise, for color,
color index, normal, and texture coordinates. However, the evaluated
values do not update the current values. Thus, if glVertex commands are
interspersed with glEvalCoord commands, the color, normal, and texture
coordinates associated with the glVertex commands are not affected by the
values generated by the glEvalCoord commands, but rather only by the most
recent glColor, glIndex, glNormal, and glTexCoord commands.
No commands are issued for maps that are not enabled. If more than one
texture evaluation is enabled for a particular dimension (for example,
GL_MAP2_TEXTURE_COORD_1 and GL_MAP2_TEXTURE_COORD_2), then only the
evaluation of the map that produces the larger number of coordinates (in
this case, GL_MAP2_TEXTURE_COORD_2) is carried out. GL_MAP1_VERTEX_4
overrides GL_MAP1_VERTEX_3, and GL_MAP2_VERTEX_4 overrides
GL_MAP2_VERTEX_3, in the same manner. If neither a three- nor four-
component vertex map is enabled for the specified dimension, the
glEvalCoord command is ignored.
If automatic normal generation is enabled, by calling glEnable with
argument GL_AUTO_NORMAL, glEvalCoord2 generates surface normals
analytically, regardless of the contents or enabling of the GL_MAP2_NORMAL
map. Let
Dp Dp
m = -- Γòû --
Du Dv
where D represents the partial differential operator.
Then the generated normal n is
m
n = -----
||m||
If automatic normal generation is disabled, the corresponding normal map
GL_MAP2_NORMAL, if enabled, is used to produce a normal. If neither
automatic normal generation nor a normal map is enabled, no normal is
generated for glEvalCoord2 commands.
Associated Gets
glIsEnabled with argument GL_MAP1_VERTEX_3
glIsEnabled with argument GL_MAP1_VERTEX_4
glIsEnabled with argument GL_MAP1_INDEX
glIsEnabled with argument GL_MAP1_COLOR_4
glIsEnabled with argument GL_MAP1_NORMAL
glIsEnabled with argument GL_MAP1_TEXTURE_COORD_1
glIsEnabled with argument GL_MAP1_TEXTURE_COORD_2
glIsEnabled with argument GL_MAP1_TEXTURE_COORD_3
glIsEnabled with argument GL_MAP1_TEXTURE_COORD_4
glIsEnabled with argument GL_MAP2_VERTEX_3
glIsEnabled with argument GL_MAP2_VERTEX_4
glIsEnabled with argument GL_MAP2_INDEX
glIsEnabled with argument GL_MAP2_COLOR_4
glIsEnabled with argument GL_MAP2_NORMAL
glIsEnabled with argument GL_MAP2_TEXTURE_COORD_1
glIsEnabled with argument GL_MAP2_TEXTURE_COORD_2
glIsEnabled with argument GL_MAP2_TEXTURE_COORD_3
glIsEnabled with argument GL_MAP2_TEXTURE_COORD_4
glIsEnabled with argument GL_AUTO_NORMAL
glGetMap
See Also
glBegin, glColor, glEnable, glEvalMesh, glEvalPoint, glIndex, glMap1,
glMap2, glMapGrid, glNormal, glTexCoord, glVertex
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Introduction | Alphabetic | Specification
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ΓòÉΓòÉΓòÉ 3.33. glEvalMesh ΓòÉΓòÉΓòÉ
OpenGL man pages
glEvalMesh
Name
glEvalMesh1, glEvalMesh2 - compute a one- or two-dimensional grid of points
or lines
C Specification
void glEvalMesh1( GLenum mode,
GLint i1,
GLint i2 )
Parameters
mode In glEvalMesh1, specifies whether to compute a one-dimensional mesh
of points or lines. Symbolic constants GL_POINT and GL_LINE are
accepted.
i1, i2
Specify the first and last integer values for grid domain variable i.
C Specification
void glEvalMesh2( GLenum mode,
GLint i1,
GLint i2,
GLint j1,
GLint j2 )
Parameters
mode In glEvalMesh2, specifies whether to compute a two-dimensional mesh of
points, lines, or polygons. Symbolic constants GL_POINT, GL_LINE, and
GL_FILL are accepted.
i1, i2
Specify the first and last integer values for grid domain variable i.
j1, j2
Specify the first and last integer values for grid domain variable j.
Description
glMapGrid and glEvalMesh are used in tandem to efficiently generate and
evaluate a series of evenly spaced map domain values. glEvalMesh steps
through the integer domain of a one- or two-dimensional grid, whose range
is the domain of the evaluation maps specified by glMap1 and glMap2. mode
determines whether the resulting vertices are connected as points, lines,
or filled polygons.
In the one-dimensional case, glEvalMesh1, the mesh is generated as if the
following code fragment were executed:
glBegin(type);
for (i = i1; i <= i2; i += 1)
glEvalCoord1(i Γòû du + u1)
glEnd();
where
du = (u2-u1)/n
and n, u1, and u2 are the arguments to the most recent glMapGrid1 command.
type is GL_POINT if mode is GL_POINT, or GL_LINES if mode is GL_LINE. The
one absolute numeric requirement is that if i = n, then the value computed
from iΓòûdu + u1 is exactly u2.
In the two-dimensional case, glEvalMesh2, let
du = (u2-u1)/n
dv = (v2-v1)/m
where n, u1, u2, m, v1, and v2 are the arguments to the most recent
glMapGrid2 comand. Then, if mode is GL_FILL, the glEvalMesh2 command is
equivalent to:
for (j = j1; j < j2; j += 1) {
glBegin(GL_QUAD_STRIP);
for (i = i1; i <= i2; i += 1) {
glEvalCoord2(iΓòûdu + u1, jΓòûdv + v1);
glEvalCoord2(iΓòûdu + u1, (j+1)Γòûdv + v1);
}
glEnd();
}
If mode is GL_LINE, then a call to glEvalMesh2 is equivalent to:
for (j = j1; j <= j2; j += 1) {
glBegin(GL_LINE_STRIP);
for (i = i1; i <= i2; i += 1)
glEvalCoord2(iΓòûdu + u1, jΓòûdv + v1);
glEnd();
}
for (i = i1; i <= i2; i += 1) {
glBegin(GL_LINE_STRIP);
for (j = j1; j <= j1; j += 1)
glEvalCoord2(iΓòûdu + u1, jΓòûdv + v1);
glEnd();
}
And finally, if mode is GL_POINT, then a call to glEvalMesh2 is equivalent
to:
glBegin(GL_POINTS);
for (j = j1; j <= j2; j += 1) {
for (i = i1; i <= i2; i += 1) {
glEvalCoord2(iΓòûdu + u1, jΓòûdv + v1);
}
}
glEnd();
In all three cases, the only absolute numeric requirements are that if
i = n, then the value computed from iΓòûdu + u1 is exactly u2, and if j = m,
then the value computed from jΓòûdv + v1 is exactly v2.
Errors
GL_INVALID_ENUM is generated if mode is not an accepted value.
GL_INVALID_OPERATION is generated if glEvalMesh is called between a call to
glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_MAP1_GRID_DOMAIN
glGet with argument GL_MAP2_GRID_DOMAIN
glGet with argument GL_MAP1_GRID_SEGMENTS
glGet with argument GL_MAP2_GRID_SEGMENTS
See Also
glBegin, glEvalCoord, glEvalPoint, glMap1, glMap2, glMapGrid
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.34. glEvalPoint ΓòÉΓòÉΓòÉ
OpenGL man pages
glEvalPoint
Name
glEvalPoint1, glEvalPoint2 - generate and evaluate a single point in a mesh
C Specification
void glEvalPoint1( GLint i )
void glEvalPoint2( GLint i,
GLint j )
Parameters
i Specifies the integer value for grid domain variable i.
j Specifies the integer value for grid domain variable j (glEvalPoint2
only).
Description
glMapGrid and glEvalMesh are used in tandem to efficiently generate and
evaluate a series of evenly spaced map domain values. glEvalPoint can be
used to evaluate a single grid point in the same gridspace that is
traversed by glEvalMesh. Calling glEvalPoint1 is equivalent to calling
glEvalCoord1(iΓòûdu + u );
1
where
du = (u -u )/n
2 1
and n, u , and u are the arguments to the most recent glMapGrid1 command.
1 2
The one absolute numeric requirement is that if i = n, then the value
computed from iΓòûdu + u is exactly u .
1 2
In the two-dimensional case, glEvalPoint2, let
du=(u -u )/n
2 1
dv=(v -v )/m
2 1
where n, u , u , m, v , and v are the arguments to the most recent
1 2 1 2
glMapGrid2 command. Then the glEvalPoint2 command is equivalent to calling
glEvalCoord2(iΓòûdu + u , jΓòûdv + v );
1 1
The only absolute numeric requirements are that if i = n, then the value
computed from iΓòûdu + u is exactly u , and if j = m, then the value
1 2
computed from jΓòûdv + v is exactly v .
1 2
Associated Gets
glGet with argument GL_MAP1_GRID_DOMAIN
glGet with argument GL_MAP2_GRID_DOMAIN
glGet with argument GL_MAP1_GRID_SEGMENTS
glGet with argument GL_MAP2_GRID_SEGMENTS
See Also
glEvalCoord, glEvalMesh, glMap1, glMap2, glMapGrid
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.35. glFeedbackBuffer ΓòÉΓòÉΓòÉ
OpenGL man pages
glFeedbackBuffer
Name
glFeedbackBuffer - controls feedback mode
C Specification
void glFeedbackBuffer( GLsizei size,
GLenum type,
GLfloat *buffer )
Parameters
size Specifies the maximum number of values that can be written into
buffer.
type Specifies a symbolic constant that describes the information that
will be returned for each vertex. GL_2D, GL_3D, GL_3D_COLOR,
GL_3D_COLOR_TEXTURE, and GL_4D_COLOR_TEXTURE are accepted.
buffer Returns the feedback data.
Description
The glFeedbackBuffer function controls feedback. Feedback, like selection,
is a GL mode. The mode is selected by calling glRenderMode with
GL_FEEDBACK. When the GL is in feedback mode, no pixels are produced by
rasterization. Instead, information about primitives that would have been
rasterized is fed back to the application using the GL.
glFeedbackBuffer has three arguments: buffer is a pointer to an array of
floating-point values into which feedback information is placed. size
indicates the size of the array. type is a symbolic constant describing
the information that is fed back for each vertex. glFeedbackBuffer must be
issued before feedback mode is enabled (by calling glRenderMode with
argument GL_FEEDBACK). Setting GL_FEEDBACK without establishing the
feedback buffer, or calling glFeedbackBuffer while the GL is in feedback
mode, is an error.
The GL is taken out of feedback mode by calling glRenderMode with a
parameter value other than GL_FEEDBACK. When this is done while the GL is
in feedback mode, glRenderMode returns the number of entries placed in the
feedback array. The returned value never exceeds size. If the feedback
data required more room than was available in buffer, glRenderMode returns
a negative value.
While in feedback mode, each primitive that would be rasterized generates a
block of values that get copied into the feedback array. If doing so would
cause the number of entries to exceed the maximum, the block is partially
written so as to fill the array (if there is any room left at all), and an
overflow flag is set. Each block begins with a code indicating the
primitive type, followed by values that describe the primitive's vertices
and associated data. Entries are also written for bitmaps and pixel
rectangles. Feedback occurs after polygon culling and glPolyMode
interpretation of polygons has taken place, so polygons that are culled are
not returned in the feedback buffer. It can also occur after polygons with
more than three edges are broken up into triangles, if the GL
implementation renders polygons by performing this decomposition.
The glPassThrough command can be used to insert a marker into the feedback
buffer. See glPassThrough.
Following is the grammar for the blocks of values written into the feedback
buffer. Each primitive is indicated with a unique identifying value
followed by some number of vertices. Polygon entries include an integer
value indicating how many vertices follow. A vertex is fed back as some
number of floating-point values, as determined by type. Colors are fed
back as four values in RGBA mode and one value in color index mode.
feedbackList <- feedbackItem feedbackList | feedbackItem
feedbackItem <- point | lineSegment | polygon | bitmap |
pixelRectangle | passThru
point <- GL_POINT_TOKEN vertex
lineSegment <- GL_LINE_TOKEN vertex vertex | GL_LINE_RESET_TOKEN
vertex vertex
polygon <- GL_POLYGON_TOKEN n polySpec
polySpec <- polySpec vertex | vertex vertex vertex
bitmap <- GL_BITMAP_TOKEN vertex
pixelRectangle <- GL_DRAW_PIXEL_TOKEN vertex | GL_COPY_PIXEL_TOKEN
vertex
passThru <- GL_PASS_THROUGH_TOKEN value
vertex <- 2d | 3d | 3dColor | 3dColorTexture | 4dColorTexture
2d <- value value
3d <- value value value
3dColor <- value value value color
3dColorTexture <- value value value color tex
4dColorTexture <- value value value value color tex
color <- rgba | index
rgba <- value value value value
index <- value
tex <- value value value value
value is a floating-point number, and n is a floating-point integer giving
the number of vertices in the polygon. GL_POINT_TOKEN, GL_LINE_TOKEN,
GL_LINE_RESET_TOKEN, GL_POLYGON_TOKEN, GL_BITMAP_TOKEN,
GL_DRAW_PIXEL_TOKEN, GL_COPY_PIXEL_TOKEN and GL_PASS_THROUGH_TOKEN are
symbolic floating-point constants. GL_LINE_RESET_TOKEN is returned
whenever the line stipple pattern is reset. The data returned as a vertex
depends on the feedback type.
The following table gives the correspondence between type and the number of
values per vertex. k is 1 in color index mode and 4 in RGBA mode.
------------------------------------------------------------------------------
| type | coordinates | color | texture | total number of values |
------------------------------------------------------------------------------
| GL_2D | x, y | | | 2 |
| GL_3D | x, y, z | | | 3 |
| GL_3D_COLOR | x, y, z | k | | 3+k |
|GL_3D_COLOR_TEXTURE | x, y, z, | k | 4 | 7+k |
|GL_4D_COLOR_TEXTURE | x, y, z, w | k | 4 | 8+k |
------------------------------------------------------------------------------
Feedback vertex coordinates are in window coordinates, except w, which is
in clip coordinates. Feedback colors are lighted, if lighting is enabled.
Feedback texture coordinates are generated, if texture coordinate
generation is enabled. They are always transformed by the texture matrix.
Notes
glFeedbackBuffer, when used in a display list, is not compiled into the
display list but rather is executed immediately.
Errors
GL_INVALID_ENUM is generated if type is not an accepted value.
GL_INVALID_VALUE is generated if size is negative.
GL_INVALID_OPERATION is generated if glFeedbackBuffer is called while the
render mode is GL_FEEDBACK, or if glRenderMode is called with argument
GL_FEEDBACK before glFeedbackBuffer is called at least once.
GL_INVALID_OPERATION is generated if glFeedbackBuffer is executed between
the execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_RENDER_MODE
See Also
glBegin, glLineStipple, glPassThrough, glPolygonMode, glRenderMode,
glSelectBuffer
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.36. glFinish ΓòÉΓòÉΓòÉ
OpenGL man pages
glFinish
Name
glFinish - block until all GL execution is complete
C Specification
void glFinish( void )
Description
glFinish does not return until the effects of all previously called GL
commands are complete. Such effects include all changes to GL state, all
changes to connection state, and all changes to the frame buffer contents.
Notes
glFinish requires a round trip to the server.
Errors
GL_INVALID_OPERATION is generated if glFinish is executed between the
execution of glBegin and the corresponding execution of glEnd.
See Also
glFlush, glXWaitGL, glXWaitX
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.37. glFlush ΓòÉΓòÉΓòÉ
OpenGL man pages
glFlush
Name
glFlush - force execution of GL commands in finite time
C Specification
void glFlush( void )
Description
Different GL implementations buffer commands in several different
locations, including network buffers and the graphics accelerator itself.
glFlush empties all of these buffers, causing all issued commands to be
executed as quickly as they are accepted by the actual rendering engine.
Though this execution may not be completed in any particular time period,
it does complete in finite time.
Because any GL program might be executed over a network, or on an
accelerator that buffers commands, all programs should call glFlush
whenever they count on having all of their previously issued commands
completed. For example, call glFlush before waiting for user input that
depends on the generated image.
Notes
glFlush can return at any time. It does not wait until the execution of
all previously issued OpenGL commands is complete.
Errors
GL_INVALID_OPERATION is generated if glFlush is executed between the
execution of glBegin and the corresponding execution of glEnd.
See Also
glFinish
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ΓòÉΓòÉΓòÉ 3.38. glFog ΓòÉΓòÉΓòÉ
OpenGL man pages
glFog
Name
glFogf, glFogi, glFogfv, glFogiv - specify fog parameters
C Specification
void glFogf( GLenum pname,
GLfloat param )
void glFogi( GLenum pname,
GLint param )
Parameters
pname Specifies a single-valued fog parameter. GL_FOG_MODE,
GL_FOG_DENSITY, GL_FOG_START, GL_FOG_END, and GL_FOG_INDEX are
accepted.
param Specifies the value that pname will be set to.
C Specification
void glFogfv( GLenum pname,
const GLfloat *params )
void glFogiv( GLenum pname,
const GLint *params )
Parameters
pname
Specifies a fog parameter. GL_FOG_MODE, GL_FOG_DENSITY, GL_FOG_START,
GL_FOG_END, GL_FOG_INDEX, and GL_FOG_COLOR are accepted.
params
Specifies the value or values to be assigned to pname. GL_FOG_COLOR
requires an array of four values. All other parameters accept an
array containing only a single value.
Description
Fog is enabled and disabled with glEnable and glDisable using the argument
GL_FOG. While enabled, fog affects rasterized geometry, bitmaps, and pixel
blocks, but not buffer clear operations.
glFog assigns the value or values in params to the fog parameter specified
by pname. The accepted values for pname are as follows:
GL_FOG_MODE params is a single integer or floating-point value that
specifies the equation to be used to compute the fog
blend factor, f. Three symbolic constants are
accepted: GL_LINEAR, GL_EXP, and GL_EXP2. The
equations corresponding to these symbolic constants are
defined below. The default fog mode is GL_EXP.
GL_FOG_DENSITY params is a single integer or floating-point value that
specifies density, the fog density used in both
exponential fog equations. Only nonnegative densities
are accepted. The default fog density is 1.0.
GL_FOG_START params is a single integer or floating-point value that
specifies start, the near distance used in the linear
fog equation. The default near distance is 0.0.
GL_FOG_END params is a single integer or floating-point value that
specifies end, the far distance used in the linear fog
equation. The default far distance is 1.0.
GL_FOG_INDEX params is a single integer or floating-point value that
specifies i , the fog color index. The default fog
f
index is 0.0.
GL_FOG_COLOR params contains four integer or floating-point values
that specify C , the fog color. Integer values are
f
mapped linearly such that the most positive
representable value maps to 1.0, and the most negative
representable value maps to -1.0. Floating-point
values are mapped directly. After conversion, all
color components are clamped to the range [0,1]. The
default fog color is (0,0,0,0).
Fog blends a fog color with each rasterized pixel fragment's posttexturing
color using a blending factor f. Factor f is computed in one of three
ways, depending on the fog mode. Let z be the distance in eye coordinates
from the origin to the fragment being fogged. The equation for GL_LINEAR
fog is
end - z
f = -----------
end - start
The equation for GL_EXP fog is
-(density Γòû z)
f = e
The equation for GL_EXP2 fog is
2
-(density Γòû z)
f = e
Regardless of the fog mode, f is clamped to the range [0,1] after it is
computed. Then, if the GL is in RGBA color mode, the fragment's color Cr
is replaced by
C' = fC +(1-f)C
r r f
In color index mode, the fragment's color index i is replaced by
r
i' = i +(1-f)i
r r f
Errors
GL_INVALID_ENUM is generated if pname is not an accepted value, or if pname
is GL_FOG_MODE and params is not an accepted value.
GL_INVALID_VALUE is generated if pname is GL_FOG_DENSITY and params is
negative.
GL_INVALID_OPERATION is generated if glFog is called between a call to
glBegin and the corresponding call to glEnd.
Associated Gets
glIsEnabled with argument GL_FOG
glGet with argument GL_FOG_COLOR
glGet with argument GL_FOG_INDEX
glGet with argument GL_FOG_DENSITY
glGet with argument GL_FOG_START
glGet with argument GL_FOG_END
glGet with argument GL_FOG_MODE
See Also
glEnable
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ΓòÉΓòÉΓòÉ 3.39. glFrontFace ΓòÉΓòÉΓòÉ
OpenGL man pages
glFrontFace
Name
glFrontFace - define front- and back-facing polygons
C Specification
void glFrontFace( GLenum mode )
Parameters
mode Specifies the orientation of front-facing polygons. GL_CW and GL_CCW
are accepted. The default value is GL_CCW.
Description
In a scene composed entirely of opaque closed surfaces, back-facing
polygons are never visible. Eliminating these invisible polygons has the
obvious benefit of speeding up the rendering of the image. Elimination of
back-facing polygons is enabled and disabled with glEnable and glDisable
using argument GL_CULL_FACE.
The projection of a polygon to window coordinates is said to have clockwise
winding if an imaginary object following the path from its first vertex,
its second vertex, and so on, to its last vertex, and finally back to its
first vertex, moves in a clockwise direction about the interior of the
polygon. The polygon's winding is said to be counterclockwise if the
imaginary object following the same path moves in a counterclockwise
direction about the interior of the polygon. glFrontFace specifies whether
polygons with clockwise winding in window coordinates, or counterclockwise
winding in window coordinates, are taken to be front-facing. Passing
GL_CCW to mode selects counterclockwise polygons as front-facing; GL_CW
selects clockwise polygons as front-facing. By default, counterclockwise
polygons are taken to be front-facing.
Errors
GL_INVALID_ENUM is generated if mode is not an accepted value.
GL_INVALID_OPERATION is generated if glFrontFace is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_FRONT_FACE
See Also
glCullFace, glLightModel
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ΓòÉΓòÉΓòÉ 3.40. glFrustum ΓòÉΓòÉΓòÉ
OpenGL man pages
glFrustum
Name
glFrustum - multiply the current matrix by a perspective matrix
C Specification
void glFrustum( GLdouble left,
GLdouble right,
GLdouble bottom,
GLdouble top,
GLdouble near,
GLdouble far )
Parameters
left, right Specify the coordinates for the left and right vertical
clipping planes.
bottom, top Specify the coordinates for the bottom and top horizontal
clipping planes.
near, far Specify the distances to the near and far depth clipping
planes. Both distances must be positive.
Description
glFrustum describes a perspective matrix that produces a perspective
projection. (left, bottom, -near) and (right, top, -near) specify the
points on the near clipping plane that are mapped to the lower left and
upper right corners of the window, respectively, assuming that the eye is
located at (0, 0, 0). -far specifies the location of the far clipping
plane. Both near and far must be positive. The corresponding matrix is
| |
| 2Γòûnear |
| ---------- |
| right-left 0 A 0 |
| |
| 0 2Γòûnear B 0 |
| ---------- |
| top-bottom |
| 0 0 C D |
| |
| 0 0 -1 0 |
right+left
A = ----------
right-left
top+bottom
B = ----------
top-bottom
far+near
C = - --------
far-near
2ΓòûfarΓòûnear
D = - ----------
far-near
The current matrix is multiplied by this matrix with the result replacing
the current matrix. That is, if M is the current matrix and F is the
frustum perspective matrix, then M is replaced with MΓòûF.
Use glPushMatrix and glPopMatrix to save and restore the current matrix
stack.
Notes
Depth buffer precision is affected by the values specified for near and
far. The greater the ratio of far to near is, the less effective the depth
buffer will be at distinguishing between surfaces that are near each other.
If
far
r = ----
near
roughly log r bits of depth buffer precision are lost. Because r
2
approaches infinity as near approaches zero, near must never be set to
zero.
Errors
GL_INVALID_VALUE is generated if near or far is not positive.
GL_INVALID_OPERATION is generated if glFrustum is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glOrtho, glMatrixMode, glMultMatrix, glPushMatrix, glViewport
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ΓòÉΓòÉΓòÉ 3.41. glGenLists ΓòÉΓòÉΓòÉ
OpenGL man pages
glGenLists
Name
glGenLists - generate a contiguous set of empty display lists
C Specification
GLuint glGenLists( GLsizei range )
Parameters
range Specifies the number of contiguous empty display lists to be
generated.
Description
glGenLists has one argument, range. It returns an integer n such that
range contiguous empty display lists, named n, n+1, ..., n+range -1, are
created. If range is zero, if there is no group of range contiguous names
available, or if any error is generated, no display lists are generated,
and zero is returned.
Errors
GL_INVALID_VALUE is generated if range is negative.
GL_INVALID_OPERATION is generated if glGenLists is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glIsList
See Also
glCallList, glCallLists, glDeleteLists, glNewList
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ΓòÉΓòÉΓòÉ 3.42. glGet ΓòÉΓòÉΓòÉ
OpenGL man pages
glGet
Name
glGetBooleanv, glGetDoublev, glGetFloatv, glGetIntegerv - return the value
or values of a selected parameter
C Specification
void glGetBooleanv( GLenum pname,
GLboolean *params )
C Specification
void glGetDoublev( GLenum pname,
GLdouble *params )
C Specification
void glGetFloatv( GLenum pname,
GLfloat *params )
C Specification
void glGetIntegerv( GLenum pname,
GLint *params )
Parameters
pname Specifies the parameter value to be returned. The symbolic
constants in the list below are accepted.
params Returns the value or values of the specified parameter.
Description
These four commands return values for simple state variables in GL. pname
is a symbolic constant indicating the state variable to be returned, and
params is a pointer to an array of the indicated type in which to place the
returned data.
Type conversion is performed if params has a different type than the state
variable value being requested. If glGetBooleanv is called, a floating-
point or integer value is converted to GL_FALSE if and only if it is zero.
Otherwise, it is converted to GL_TRUE. If glGetIntegerv is called, Boolean
values are returned as GL_TRUE or GL_FALSE, and most floating-point values
are rounded to the nearest integer value. Floating-point colors and
normals, however, are returned with a linear mapping that maps 1.0 to the
most positive representable integer value, and -1.0 to the most negative
representable integer value. If glGetFloatv or glGetDoublev is called,
Boolean values are returned as GL_TRUE or GL_FALSE, and integer values are
converted to floating-point values.
The following symbolic constants are accepted by pname:
GL_ACCUM_ALPHA_BITS params returns one value, the number of alpha
bitplanes in the accumulation buffer.
GL_ACCUM_BLUE_BITS params returns one value, the number of blue
bitplanes in the accumulation buffer.
GL_ACCUM_CLEAR_VALUE params returns four values: the red, green, blue,
and alpha values used to clear the accumulation
buffer. Integer values, if requested, are
linearly mapped from the internal floating-point
representation such that 1.0 returns the most
positive representable integer value, and -1.0
returns the most negative representable integer
value. See glClearAccum.
GL_ACCUM_GREEN_BITS params returns one value, the number of green
bitplanes in the accumulation buffer.
GL_ACCUM_RED_BITS params returns one value, the number of red
bitplanes in the accumulation buffer.
GL_ALPHA_BIAS params returns one value, the alpha bias factor
used during pixel transfers. See glPixelTransfer.
GL_ALPHA_BITS params returns one value, the number of alpha
bitplanes in each color buffer.
GL_ALPHA_SCALE params returns one value, the alpha scale factor
used during pixel transfers. See glPixelTransfer.
GL_ALPHA_TEST params returns a single Boolean value indicating
whether alpha testing of fragments is enabled.
See glAlphaFunc.
GL_ALPHA_TEST_FUNC params returns one value, the symbolic name of the
alpha test function. See glAlphaFunc.
GL_ALPHA_TEST_REF params returns one value, the reference value for
the alpha test. See glAlphaFunc. An integer
value, if requested, is linearly mapped from the
internal floating-point representation such that
1.0 returns the most positive representable
integer value, and -1.0 returns the most negative
representable integer value.
GL_ATTRIB_STACK_DEPTH params returns one value, the depth of the
attribute stack. If the stack is empty, zero is
returned. See glPushAttrib.
GL_AUTO_NORMAL params returns a single Boolean value indicating
whether 2-D map evaluation automatically generates
surface normals. See glMap2.
GL_AUX_BUFFERS params returns one value, the number of auxiliary
color buffers.
GL_BLEND params returns a single Boolean value indicating
whether blending is enabled. See glBlendFunc.
GL_BLEND_DST params returns one value, the symbolic constant
identifying the destination blend function. See
glBlendFunc.
GL_BLEND_SRC params returns one value, the symbolic constant
identifying the source blend function. See
glBlendFunc.
GL_BLUE_BIAS params returns one value, the blue bias factor
used during pixel transfers. See glPixelTransfer.
GL_BLUE_BITS params returns one value, the number of blue
bitplanes in each color buffer.
GL_BLUE_SCALE params returns one value, the blue scale factor
used during pixel transfers. See glPixelTransfer.
GL_CLIP_PLANEi params returns a single Boolean value indicating
whether the specified clipping plane is enabled.
See glClipPlane.
GL_COLOR_ARRAY_EXT params returns a single boolean value, indicating
whether the color array is enabled. See
glColorPointerEXT.
GL_COLOR_ARRAY_COUNT_EXT params returns one value, the number of colors in
the color array, counting from the first, that are
static. See glColorPointerEXT.
GL_COLOR_ARRAY_SIZE_EXT params returns one value, the number of components
per color in the color array. See
glColorPointerEXT.
GL_COLOR_ARRAY_STRIDE_EXT
params returns one value, the byte offset between
consecutive colors in the color array. See
glColorPointerEXT.
GL_COLOR_ARRAY_TYPE_EXT params returns one value, the data type of each
component in the color array. See
glColorPointerEXT.
GL_COLOR_CLEAR_VALUE params returns four values: the red, green, blue,
and alpha values used to clear the color buffers.
Integer values, if requested, are linearly mapped
from the internal floating-point representation
such that 1.0 returns the most positive
representable integer value, and -1.0 returns the
most negative representable integer value. See
glClearColor.
GL_COLOR_MATERIAL params returns a single Boolean value indicating
whether one or more material parameters are
tracking the current color. See glColorMaterial.
GL_COLOR_MATERIAL_FACE params returns one value, a symbolic constant
indicating which materials have a parameter that
is tracking the current color. See
glColorMaterial.
GL_COLOR_MATERIAL_PARAMETER
params returns one value, a symbolic constant
indicating which material parameters are tracking
the current color. See glColorMaterial.
GL_COLOR_WRITEMASK params returns four Boolean values: the red,
green, blue, and alpha write enables for the color
buffers. See glColorMask.
GL_CULL_FACE params returns a single Boolean value indicating
whether polygon culling is enabled. See
glCullFace.
GL_CULL_FACE_MODE params returns one value, a symbolic constant
indicating which polygon faces are to be culled.
See glCullFace.
GL_CURRENT_COLOR params returns four values: the red, green, blue,
and alpha values of the current color. Integer
values, if requested, are linearly mapped from the
internal floating-point representation such that
1.0 returns the most positive representable
integer value, and -1.0 returns the most negative
representable integer value. See glColor.
GL_CURRENT_INDEX params returns one value, the current color index.
See glIndex.
GL_CURRENT_NORMAL params returns three values: the x, y, and z
values of the current normal. Integer values, if
requested, are linearly mapped from the internal
floating-point representation such that 1.0
returns the most positive representable integer
value, and -1.0 returns the most negative
representable integer value. See glNormal.
GL_CURRENT_RASTER_COLOR params returns four values: the red, green, blue,
and alpha values of the current raster position.
Integer values, if requested, are linearly mapped
from the internal floating-point representation
such that 1.0 returns the most positive
representable integer value, and -1.0 returns the
most negative representable integer value. See
glRasterPos.
GL_CURRENT_RASTER_DISTANCE
params returns one value, the distance from the
eye to the current raster position. See
glRasterPos.
GL_CURRENT_RASTER_INDEX params returns one value, the color index of the
current raster position. See glRasterPos.
GL_CURRENT_RASTER_POSITION
params returns four values: the x, y, z, and w
components of the current raster position. x, y,
and z are in window coordinates, and w is in clip
coordinates. See glRasterPos.
GL_CURRENT_RASTER_TEXTURE_COORDS
params returns four values: the s, t, r, and q
current raster texture coordinates. See
glRasterPos and glTexCoord.
GL_CURRENT_RASTER_POSITION_VALID
params returns a single Boolean value indicating
whether the current raster position is valid. See
glRasterPos.
GL_CURRENT_TEXTURE_COORDS
params returns four values: the s, t, r, and q
current texture coordinates. See glTexCoord.
GL_DEPTH_BIAS params returns one value, the depth bias factor
used during pixel transfers. See glPixelTransfer.
GL_DEPTH_BITS params returns one value, the number of bitplanes
in the depth buffer.
GL_DEPTH_CLEAR_VALUE params returns one value, the value that is used
to clear the depth buffer. Integer values, if
requested, are linearly mapped from the internal
floating-point representation such that 1.0
returns the most positive representable integer
value, and -1.0 returns the most negative
representable integer value. See glClearDepth.
GL_DEPTH_FUNC params returns one value, the symbolic constant
that indicates the depth comparison function. See
glDepthFunc.
GL_DEPTH_RANGE params returns two values: the near and far
mapping limits for the depth buffer. Integer
values, if requested, are linearly mapped from the
internal floating-point representation such that
1.0 returns the most positive representable
integer value, and -1.0 returns the most negative
representable integer value. See glDepthRange.
GL_DEPTH_SCALE params returns one value, the depth scale factor
used during pixel transfers. See glPixelTransfer.
GL_DEPTH_TEST params returns a single Boolean value indicating
whether depth testing of fragments is enabled.
See glDepthFunc and glDepthRange.
GL_DEPTH_WRITEMASK params returns a single Boolean value indicating
if the depth buffer is enabled for writing. See
glDepthMask.
GL_DITHER params returns a single Boolean value indicating
whether dithering of fragment colors and indices
is enabled.
GL_DOUBLEBUFFER params returns a single Boolean value indicating
whether double buffering is supported.
GL_DRAW_BUFFER params returns one value, a symbolic constant
indicating which buffers are being drawn to. See
glDrawBuffer.
GL_EDGE_FLAG params returns a single Boolean value indication
whether the current edge flag is true or false.
See glEdgeFlag.
GL_EDGE_FLAG_ARRAY_EXT params returns a single boolean value, indicating
whether the edge flag array is enabled. See
glEdgeFlagPointerEXT.
GL_EDGE_FLAG_ARRAY_COUNT_EXT
params returns one value, the number of edge flags
in the edge flag array, counting from the first,
that are static. See glEdgeFlagPointerEXT.
GL_EDGE_FLAG_ARRAY_STRIDE_EXT
params returns one value, the byte offset between
consecutive edge flags in the edge flag array.
See glEdgeFlagPointerEXT.
GL_FOG params returns a single Boolean value indicating
whether fogging is enabled. See glFog.
GL_FOG_COLOR params returns four values: the red, green, blue,
and alpha components of the fog color. Integer
values, if requested, are linearly mapped from the
internal floating-point representation such that
1.0 returns the most positive representable
integer value, and -1.0 returns the most negative
representable integer value. See glFog.
GL_FOG_DENSITY params returns one value, the fog density
parameter. See glFog.
GL_FOG_END params returns one value, the end factor for the
linear fog equation. See glFog.
GL_FOG_HINT params returns one value, a symbolic constant
indicating the mode of the fog hint. See glHint.
GL_FOG_INDEX params returns one value, the fog color index.
See glFog.
GL_FOG_MODE params returns one value, a symbolic constant
indicating which fog equation is selected. See
glFog.
GL_FOG_START params returns one value, the start factor for the
linear fog equation. See glFog.
GL_FRONT_FACE params returns one value, a symbolic constant
indicating whether clockwise or counterclockwise
polygon winding is treated as front-facing. See
glFrontFace.
GL_GREEN_BIAS params returns one value, the green bias factor
used during pixel transfers.
GL_GREEN_BITS params returns one value, the number of green
bitplanes in each color buffer.
GL_GREEN_SCALE params returns one value, the green scale factor
used during pixel transfers. See glPixelTransfer.
GL_INDEX_ARRAY_EXT params returns a single boolean value, indicating
whether the color index array is enabled. See
glIndexPointerEXT.
GL_INDEX_ARRAY_COUNT_EXT params returns one value, the number of color
indexes in the color index array, counting from
the first, that are static. See
glIndexPointerEXT.
GL_INDEX_ARRAY_STRIDE_EXT
params returns one value, the byte offset between
consecutive color indexes in the color index
array. See glIndexPointerEXT.
GL_INDEX_ARRAY_TYPE_EXT params returns one value, the data type of indexes
in the color index array. See glIndexPointerEXT.
GL_INDEX_BITS params returns one value, the number of bitplanes
in each color index buffer.
GL_INDEX_CLEAR_VALUE params returns one value, the color index used to
clear the color index buffers. See glClearIndex.
GL_INDEX_MODE params returns a single Boolean value indicating
whether the GL is in color index mode (true) or
RGBA mode (false).
GL_INDEX_OFFSET params returns one value, the offset added to
color and stencil indices during pixel transfers.
See glPixelTransfer.
GL_INDEX_SHIFT params returns one value, the amount that color
and stencil indices are shifted during pixel
transfers. See glPixelTransfer.
GL_INDEX_WRITEMASK params returns one value, a mask indicating which
bitplanes of each color index buffer can be
written. See glIndexMask.
GL_LIGHTi params returns a single Boolean value indicating
whether the specified light is enabled. See
glLight and glLightModel.
GL_LIGHTING params returns a single Boolean value indicating
whether lighting is enabled. See glLightModel.
GL_LIGHT_MODEL_AMBIENT params returns four values: the red, green, blue,
and alpha components of the ambient intensity of
the entire scene. Integer values, if requested,
are linearly mapped from the internal floating-
point representation such that 1.0 returns the
most positive representable integer value, and
-1.0 returns the most negative representable
integer value. See glLightModel.
GL_LIGHT_MODEL_LOCAL_VIEWER
params returns a single Boolean value indicating
whether specular reflection calculations treat the
viewer as being local to the scene. See
glLightModel.
GL_LIGHT_MODEL_TWO_SIDE params returns a single Boolean value indicating
whether separate materials are used to compute
lighting for front- and back-facing polygons. See
glLightModel.
GL_LINE_SMOOTH params returns a single Boolean value indicating
whether antialiasing of lines is enabled. See
glLineWidth.
GL_LINE_SMOOTH_HINT params returns one value, a symbolic constant
indicating the mode of the line antialiasing hint.
See glHint.
GL_LINE_STIPPLE params returns a single Boolean value indicating
whether stippling of lines is enabled. See
glLineStipple.
GL_LINE_STIPPLE_PATTERN params returns one value, the 16-bit line stipple
pattern. See glLineStipple.
GL_LINE_STIPPLE_REPEAT params returns one value, the line stipple repeat
factor. See glLineStipple.
GL_LINE_WIDTH params returns one value, the line width as
specified with glLineWidth.
GL_LINE_WIDTH_GRANULARITY
params returns one value, the width difference
between adjacent supported widths for antialiased
lines. See glLineWidth.
GL_LINE_WIDTH_RANGE params returns two values: the smallest and
largest supported widths for antialiased lines.
See glLineWidth.
GL_LIST_BASE params returns one value, the base offset added to
all names in arrays presented to glCallLists. See
glListBase.
GL_LIST_INDEX params returns one value, the name of the display
list currently under construction. Zero is
returned if no display list is currently under
construction. See glNewList.
GL_LIST_MODE params returns one value, a symbolic constant
indicating the construction mode of the display
list currently being constructed. See glNewList.
GL_LOGIC_OP params returns a single Boolean value indicating
whether fragment indexes are merged into the
framebuffer using a logical operation. See
glLogicOp.
GL_LOGIC_OP_MODE params returns one value, a symbolic constant
indicating the selected logic operational mode.
See glLogicOp.
GL_MAP1_COLOR_4 params returns a single Boolean value indicating
whether 1D evaluation generates colors. See
glMap1.
GL_MAP1_GRID_DOMAIN params returns two values: the endpoints of the
1-D map's grid domain. See glMapGrid.
GL_MAP1_GRID_SEGMENTS params returns one value, the number of partitions
in the 1-D map's grid domain. See glMapGrid.
GL_MAP1_INDEX params returns a single Boolean value indicating
whether 1D evaluation generates color indices.
See glMap1.
GL_MAP1_NORMAL params returns a single Boolean value indicating
whether 1D evaluation generates normals. See
glMap1.
GL_MAP1_TEXTURE_COORD_1 params returns a single Boolean value indicating
whether 1D evaluation generates 1D texture
coordinates. See glMap1.
GL_MAP1_TEXTURE_COORD_2 params returns a single Boolean value indicating
whether 1D evaluation generates 2D texture
coordinates. See glMap1.
GL_MAP1_TEXTURE_COORD_3 params returns a single Boolean value indicating
whether 1D evaluation generates 3D texture
coordinates. See glMap1.
GL_MAP1_TEXTURE_COORD_4 params returns a single Boolean value indicating
whether 1D evaluation generates 4D texture
coordinates. See glMap1.
GL_MAP1_VERTEX_3 params returns a single Boolean value indicating
whether 1D evaluation generates 3D vertex
coordinates. See glMap1.
GL_MAP1_VERTEX_4 params returns a single Boolean value indicating
whether 1D evaluation generates 4D vertex
coordinates. See glMap1.
GL_MAP2_COLOR_4 params returns a single Boolean value indicating
whether 2D evaluation generates colors. See
glMap2.
GL_MAP2_GRID_DOMAIN params returns four values: the endpoints of the
2-D map's i and j grid domains. See glMapGrid.
GL_MAP2_GRID_SEGMENTS params returns two values: the number of
partitions in the 2-D map's i and j grid domains.
See glMapGrid.
GL_MAP2_INDEX params returns a single Boolean value indicating
whether 2D evaluation generates color indices.
See glMap2.
GL_MAP2_NORMAL params returns a single Boolean value indicating
whether 2D evaluation generates normals. See
glMap2.
GL_MAP2_TEXTURE_COORD_1 params returns a single Boolean value indicating
whether 2D evaluation generates 1D texture
coordinates. See glMap2.
GL_MAP2_TEXTURE_COORD_2 params returns a single Boolean value indicating
whether 2D evaluation generates 2D texture
coordinates. See glMap2.
GL_MAP2_TEXTURE_COORD_3 params returns a single Boolean value indicating
whether 2D evaluation generates 3D texture
coordinates. See glMap2.
GL_MAP2_TEXTURE_COORD_4 params returns a single Boolean value indicating
whether 2D evaluation generates 4D texture
coordinates. See glMap2.
GL_MAP2_VERTEX_3 params returns a single Boolean value indicating
whether 2D evaluation generates 3D vertex
coordinates. See glMap2.
GL_MAP2_VERTEX_4 params returns a single Boolean value indicating
whether 2D evaluation generates 4D vertex
coordinates. See glMap2.
GL_MAP_COLOR params returns a single Boolean value indicating
if colors and color indices are to be replaced by
table lookup during pixel transfers. See
glPixelTransfer.
GL_MAP_STENCIL params returns a single Boolean value indicating
if stencil indices are to be replaced by table
lookup during pixel transfers. See
glPixelTransfer.
GL_MATRIX_MODE params returns one value, a symbolic constant
indicating which matrix stack is currently the
target of all matrix operations. See
glMatrixMode.
GL_MAX_ATTRIB_STACK_DEPTH
params returns one value, the maximum supported
depth of the attribute stack. See glPushAttrib.
GL_MAX_CLIP_PLANES params returns one value, the maximum number of
application-defined clipping planes. See
glClipPlane.
GL_MAX_EVAL_ORDER params returns one value, the maximum equation
order supported by 1-D and 2-D evaluators. See
glMap1 and glMap2.
GL_MAX_LIGHTS params returns one value, the maximum number of
lights. See glLight.
GL_MAX_LIST_NESTING params returns one value, the maximum recursion
depth allowed during display-list traversal. See
glCallList.
GL_MAX_MODELVIEW_STACK_DEPTH
params returns one value, the maximum supported
depth of the modelview matrix stack. See
glPushMatrix.
GL_MAX_NAME_STACK_DEPTH params returns one value, the maximum supported
depth of the selection name stack. See
glPushName.
GL_MAX_PIXEL_MAP_TABLE params returns one value, the maximum supported
size of a glPixelMap lookup table. See
glPixelMap.
GL_MAX_PROJECTION_STACK_DEPTH
params returns one value, the maximum supported
depth of the projection matrix stack. See
glPushMatrix.
GL_MAX_TEXTURE_SIZE params returns one value, the maximum width or
height of any texture image (without borders).
See glTexImage1D and glTexImage2D.
GL_MAX_TEXTURE_STACK_DEPTH
params returns one value, the maximum supported
depth of the texture matrix stack. See
glPushMatrix.
GL_MAX_VIEWPORT_DIMS params returns two values: the maximum supported
width and height of the viewport. See glViewport.
GL_MODELVIEW_MATRIX params returns sixteen values: the modelview
matrix on the top of the modelview matrix stack.
See glPushMatrix.
GL_MODELVIEW_STACK_DEPTH params returns one value, the number of matrices
on the modelview matrix stack. See glPushMatrix.
GL_NAME_STACK_DEPTH params returns one value, the number of names on
the selection name stack. See glPushMatrix.
GL_NORMAL_ARRAY_EXT params returns a single boolean value, indicating
whether the normal array is enabled. See
glNormalPointerEXT.
GL_NORMAL_ARRAY_COUNT_EXT
params returns one value, the number of normals in
the normal array, counting from the first, that
are static. See glNormalPointerEXT.
GL_NORMAL_ARRAY_STRIDE_EXT
params returns one value, the byte offset between
consecutive normals in the normal array. See
glNormalPointerEXT.
GL_NORMAL_ARRAY_TYPE_EXT params returns one value, the data type of each
coordinate in the normal array. See
glNormalPointerEXT.
GL_NORMALIZE params returns a single Boolean value indicating
whether normals are automatically scaled to unit
length after they have been transformed to eye
coordinates. See glNormal.
GL_PACK_ALIGNMENT params returns one value, the byte alignment used
for writing pixel data to memory. See
glPixelStore.
GL_PACK_LSB_FIRST params returns a single Boolean value indicating
whether single-bit pixels being written to memory
are written first to the least significant bit of
each unsigned byte. See glPixelStore.
GL_PACK_ROW_LENGTH params returns one value, the row length used for
writing pixel data to memory. See glPixelStore.
GL_PACK_SKIP_PIXELS params returns one value, the number of pixel
locations skipped before the first pixel is
written into memory. See glPixelStore.
GL_PACK_SKIP_ROWS params returns one value, the number of rows of
pixel locations skipped before the first pixel is
written into memory. See glPixelStore.
GL_PACK_SWAP_BYTES params returns a single Boolean value indicating
whether the bytes of two-byte and four-byte pixel
indices and components are swapped before being
written to memory. See glPixelStore.
GL_PERSPECTIVE_CORRECTION_HINT
params returns one value, a symbolic constant
indicating the mode of the perspective correction
hint. See glHint.
GL_PIXEL_MAP_A_TO_A_SIZE params returns one value, the size of the alpha-
to-alpha pixel translation table. See glPixelMap.
GL_PIXEL_MAP_B_TO_B_SIZE params returns one value, the size of the blue-
to-blue pixel translation table. See glPixelMap.
GL_PIXEL_MAP_G_TO_G_SIZE params returns one value, the size of the green-
to-green pixel translation table. See glPixelMap.
GL_PIXEL_MAP_I_TO_A_SIZE params returns one value, the size of the index-
to-alpha pixel translation table. See glPixelMap.
GL_PIXEL_MAP_I_TO_B_SIZE params returns one value, the size of the index-
to-blue pixel translation table. See glPixelMap.
GL_PIXEL_MAP_I_TO_G_SIZE params returns one value, the size of the index-
to-green pixel translation table. See glPixelMap.
GL_PIXEL_MAP_I_TO_I_SIZE params returns one value, the size of the index-
to-index pixel translation table. See glPixelMap.
GL_PIXEL_MAP_I_TO_R_SIZE params returns one value, the size of the index-
to-red pixel translation table. See glPixelMap.
GL_PIXEL_MAP_R_TO_R_SIZE params returns one value, the size of the red-to-
red pixel translation table. See glPixelMap.
GL_PIXEL_MAP_S_TO_S_SIZE params returns one value, the size of the
stencil-to-stencil pixel translation table. See
glPixelMap.
GL_POINT_SIZE params returns one value, the point size as
specified by glPointSize.
GL_POINT_SIZE_GRANULARITY
params returns one value, the size difference
between adjacent supported sizes for antialiased
points. See glPointSize.
GL_POINT_SIZE_RANGE params returns two values: the smallest and
largest supported sizes for antialiased points.
See glPointSize.
GL_POINT_SMOOTH params returns a single Boolean value indicating
whether antialiasing of points is enabled. See
glPointSize.
GL_POINT_SMOOTH_HINT params returns one value, a symbolic constant
indicating the mode of the point antialiasing
hint. See glHint.
GL_POLYGON_MODE params returns two values: symbolic constants
indicating whether front-facing and back-facing
polygons are rasterized as points, lines, or
filled polygons. See glPolygonMode.
GL_POLYGON_SMOOTH params returns a single Boolean value indicating
whether antialiasing of polygons is enabled. See
glPolygonMode.
GL_POLYGON_SMOOTH_HINT params returns one value, a symbolic constant
indicating the mode of the polygon antialiasing
hint. See glHint.
GL_POLYGON_STIPPLE params returns a single Boolean value indicating
whether stippling of polygons is enabled. See
glPolygonStipple.
GL_PROJECTION_MATRIX params returns sixteen values: the projection
matrix on the top of the projection matrix stack.
See glPushMatrix.
GL_PROJECTION_STACK_DEPTH
params returns one value, the number of matrices
on the projection matrix stack. See glPushMatrix.
GL_READ_BUFFER params returns one value, a symbolic constant
indicating which color buffer is selected for
reading.
See glReadPixels and glAccum.
GL_RED_BIAS params returns one value, the red bias factor used
during pixel transfers.
GL_RED_BITS params returns one value, the number of red
bitplanes in each color buffer.
GL_RED_SCALE params returns one value, the red scale factor
used during pixel transfers. See glPixelTransfer.
GL_RENDER_MODE params returns one value, a symbolic constant
indicating whether the GL is in render, select, or
feedback mode. See glRenderMode.
GL_RGBA_MODE params returns a single Boolean value indicating
whether the GL is in RGBA mode (true) or color
index mode (false). See glColor.
GL_SCISSOR_BOX params returns four values: the x and y window
coordinates of the scissor box, followed by its
width and height. See glScissor.
GL_SCISSOR_TEST params returns a single Boolean value indicating
whether scissoring is enabled. See glScissor.
GL_SHADE_MODEL params returns one value, a symbolic constant
indicating whether the shading mode is flat or
smooth. See glShadeModel.
GL_STENCIL_BITS params returns one value, the number of bitplanes
in the stencil buffer.
GL_STENCIL_CLEAR_VALUE params returns one value, the index to which the
stencil bitplanes are cleared. See
glClearStencil.
GL_STENCIL_FAIL params returns one value, a symbolic constant
indicating what action is taken when the stencil
test fails. See glStencilOp.
GL_STENCIL_FUNC params returns one value, a symbolic constant
indicating what function is used to compare the
stencil reference value with the stencil buffer
value. See glStencilFunc.
GL_STENCIL_PASS_DEPTH_FAIL
params returns one value, a symbolic constant
indicating what action is taken when the stencil
test passes, but the depth test fails. See
glStencilOp.
GL_STENCIL_PASS_DEPTH_PASS
params returns one value, a symbolic constant
indicating what action is taken when the stencil
test passes and the depth test passes. See
glStencilOp.
GL_STENCIL_REF params returns one value, the reference value that
is compared with the contents of the stencil
buffer. See glStencilFunc.
GL_STENCIL_TEST params returns a single Boolean value indicating
whether stencil testing of fragments is enabled.
See glStencilFunc and glStencilOp.
GL_STENCIL_VALUE_MASK params returns one value, the mask that is used to
mask both the stencil reference value and the
stencil buffer value before they are compared.
See glStencilFunc.
GL_STENCIL_WRITEMASK params returns one value, the mask that controls
writing of the stencil bitplanes. glStencilMask.
GL_STEREO params returns a single Boolean value indicating
whether stereo buffers (left and right) are
supported.
GL_SUBPIXEL_BITS params returns one value, an estimate of the
number of bits of subpixel resolution that are
used to position rasterized geometry in window
coordinates.
GL_TEXTURE_1D params returns a single Boolean value indicating
whether 1D texture mapping is enabled. See
glTexImage1D.
GL_TEXTURE_2D params returns a single Boolean value indicating
whether 2D texture mapping is enabled. See
glTexImage2D.
GL_TEXTURE_COORD_ARRAY_EXT
params returns a single boolean value, indicating
whether the texture coordinate array is enabled.
See glTexCoordPointerEXT.
GL_TEXTURE_COORD_ARRAY_COUNT_EXT
params returns one value, the number of elements
in the texture coordinate array, counting from the
first, that are static. See glTexCoordPointerEXT.
GL_TEXTURE_COORD_ARRAY_SIZE_EXT
params returns one value, the number of
coordinates per element in the texture coordinate
array. See glTexCoordPointerEXT.
GL_TEXTURE_COORD_ARRAY_STRIDE_EXT
params returns one value, the byte offset between
consecutive elements in the texture coordinate
array. See glTexCoordPointerEXT.
GL_TEXTURE_COORD_ARRAY_TYPE_EXT
params returns one value, the data type of the
coordinates in the texture coordinate array. See
glTexCoordPointerEXT.
GL_TEXTURE_GEN_S params returns a single Boolean value indicating
whether automatic generation of the S texture
coordinate is enabled. See glTexGen.
GL_TEXTURE_GEN_T params returns a single Boolean value indicating
whether automatic generation of the T texture
coordinate is enabled. See glTexGen.
GL_TEXTURE_GEN_R params returns a single Boolean value indicating
whether automatic generation of the R texture
coordinate is enabled. See glTexGen.
GL_TEXTURE_GEN_Q params returns a single Boolean value indicating
whether automatic generation of the Q texture
coordinate is enabled. See glTexGen.
GL_TEXTURE_MATRIX params returns sixteen values: the texture matrix
on the top of the texture matrix stack. See
glPushMatrix.
GL_TEXTURE_STACK_DEPTH params returns one value, the number of matrices
on the texture matrix stack. See glPushMatrix.
GL_UNPACK_ALIGNMENT params returns one value, the byte alignment used
for reading pixel data from memory. See
glPixelStore.
GL_UNPACK_LSB_FIRST params returns a single Boolean value indicating
whether single-bit pixels being read from memory
are read first from the least significant bit of
each unsigned byte. See glPixelStore.
GL_UNPACK_ROW_LENGTH params returns one value, the row length used for
reading pixel data from memory. See glPixelStore.
GL_UNPACK_SKIP_PIXELS params returns one value, the number of pixel
locations skipped before the first pixel is read
from memory. See glPixelStore.
GL_UNPACK_SKIP_ROWS params returns one value, the number of rows of
pixel locations skipped before the first pixel is
read from memory. See glPixelStore.
GL_UNPACK_SWAP_BYTES params returns a single Boolean value indicating
whether the bytes of two-byte and four-byte pixel
indices and components are swapped after being
read from memory. See glPixelStore.
GL_VERTEX_ARRAY_EXT params returns a single boolean value, indicating
whether the vertex array is enabled. See
glVertexPointerEXT.
GL_VERTEX_ARRAY_COUNT_EXT
params returns one value, the number of vertexes
in the vertex array, counting from the first, that
are static. See glVertexPointerEXT.
GL_VERTEX_ARRAY_SIZE_EXT params returns one value, the number of
coordinates per vertex in the vertex array. See
glVertexPointerEXT.
GL_VERTEX_ARRAY_STRIDE_EXT
params returns one value, the byte offset between
consecutive vertexes in the vertex array. See
glVertexPointerEXT.
GL_VERTEX_ARRAY_TYPE_EXT params returns one value, the data type of each
coordinate in the vertex array. See
glVertexPointerEXT.
GL_VIEWPORT params returns four values: the x and y window
coordinates of the viewport, followed by its width
and height. See glViewport.
GL_ZOOM_X params returns one value, the x pixel zoom factor.
See glPixelZoom.
GL_ZOOM_Y params returns one value, the y pixel zoom factor.
See glPixelZoom.
Many of the Boolean parameters can also be queried more easily using
glIsEnabled.
Errors
GL_INVALID_ENUM is generated if pname is not an accepted value.
GL_INVALID_OPERATION is generated if glGet is executed between the
execution of glBegin and the corresponding execution of glEnd.
See Also
glGetClipPlane, glGetError, glGetLight, glGetMap, glGetMaterial,
glGetPixelMap, glGetPolygonStipple, glGetString, glGetTexEnv, glGetTexGen,
glGetTexImage, glGetTexLevelParameter, glGetTexParameter, glIsEnabled
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
Look here for legal stuff: Legal
ΓòÉΓòÉΓòÉ 3.43. glGetClipPlane ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetClipPlane
Name
glGetClipPlane - return the coefficients of the specified clipping plane
C Specification
void glGetClipPlane( GLenum plane,
GLdouble *equation )
Parameters
plane Specifies a clipping plane. The number of clipping planes
depends on the implementation, but at least six clipping planes
are supported. They are identified by symbolic names of the form
GL_CLIP_PLANEi where 0 <= i < GL_MAX_CLIP_PLANES.
equation Returns four double-precision values that are the coefficients of
the plane equation of plane in eye coordinates.
Description
glGetClipPlane returns in equation the four coefficients of the plane
equation for plane.
Notes
It is always the case that GL_CLIP_PLANEi = GL_CLIP_PLANE0 + i.
If an error is generated, no change is made to the contents of equation.
Errors
GL_INVALID_ENUM is generated if plane is not an accepted value.
GL_INVALID_OPERATION is generated if glGetClipPlane is executed between the
execution of glBegin and the corresponding execution of glEnd.
See Also
glClipPlane
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
Look here for legal stuff: Legal
ΓòÉΓòÉΓòÉ 3.44. glGetError ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetError
Name
glGetError - return error information
C Specification
GLenum glGetError( void )
Description
glGetError returns the value of the error flag. Each detectable error is
assigned a numeric code and symbolic name. When an error occurs, the error
flag is set to the appropriate error code value. No other errors are
recorded until glGetError is called, the error code is returned, and the
flag is reset to GL_NO_ERROR. If a call to glGetError returns GL_NO_ERROR,
there has been no detectable error since the last call to glGetError, or
since the GL was initialized.
To allow for distributed implementations, there may be several error flags.
If any single error flag has recorded an error, the value of that flag is
returned and that flag is reset to GL_NO_ERROR when glGetError is called.
If more than one flag has recorded an error, glGetError returns and clears
an arbitrary error flag value. Thus, glGetError should always be called in
a loop, until it returns GL_NO_ERROR, if all error flags are to be reset.
Initially, all error flags are set to GL_NO_ERROR.
The currently defined errors are as follows:
GL_NO_ERROR No error has been recorded. The value of
this symbolic constant is guaranteed to be
zero.
GL_INVALID_ENUM An unacceptable value is specified for an
enumerated argument. The offending command
is ignored, having no side effect other than
to set the error flag.
GL_INVALID_VALUE A numeric argument is out of range. The
offending command is ignored, having no side
effect other than to set the error flag.
GL_INVALID_OPERATION The specified operation is not allowed in the
current state. The offending command is
ignored, having no side effect other than to
set the error flag.
GL_STACK_OVERFLOW This command would cause a stack overflow.
The offending command is ignored, having no
side effect other than to set the error flag.
GL_STACK_UNDERFLOW This command would cause a stack underflow.
The offending command is ignored, having no
side effect other than to set the error flag.
GL_OUT_OF_MEMORY There is not enough memory left to execute
the command. The state of the GL is
undefined, except for the state of the error
flags, after this error is recorded.
When an error flag is set, results of a GL operation are undefined only if
GL_OUT_OF_MEMORY has occurred. In all other cases, the command generating
the error is ignored and has no effect on the GL state or frame buffer
contents. If the generating command returns a value, it returns zero. If
glGetError itself generates an error it returns zero.
Errors
GL_INVALID_OPERATION is generated if glGetError is executed between the
execution of glBegin and the corresponding execution of glEnd. In this
case glGetError returns zero.
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ΓòÉΓòÉΓòÉ 3.45. glGetLight ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetLight
Name
glGetLightfv, glGetLightiv - return light source parameter values
C Specification
void glGetLightfv( GLenum light,
GLenum pname,
GLfloat *params )
void glGetLightiv( GLenum light,
GLenum pname,
GLint *params )
Parameters
light Specifies a light source. The number of possible lights depends on
the implementation, but at least eight lights are supported. They
are identified by symbolic names of the form GL_LIGHTi where 0 <= i
< GL_MAX_LIGHTS.
pname Specifies a light source parameter for light. Accepted symbolic
names are GL_AMBIENT, GL_DIFFUSE, GL_SPECULAR, GL_POSITION,
GL_SPOT_DIRECTION, GL_SPOT_EXPONENT, GL_SPOT_CUTOFF,
GL_CONSTANT_ATTENUATION, GL_LINEAR_ATTENUATION , and
GL_QUADRATIC_ATTENUATION.
params Returns the requested data.
Description
glGetLight returns in params the value or values of a light source
parameter. light names the light and is a symbolic name of the form
GL_LIGHTi for 0<=i<GL_MAX_LIGHTS, where GL_MAX_LIGHTS is an implementation
dependent constant that is greater than or equal to eight. pname specifies
one of ten light source parameters, again by symbolic name.
The parameters are as follows:
GL_AMBIENT params returns four integer or floating-point values
representing the ambient intensity of the light source.
Integer values, when requested, are linearly mapped
from the internal floating-point representation such
that 1.0 maps to the most positive representable
integer value, and -1.0 maps to the most negative
representable integer value. If the internal value is
outside the range [-1,1], the corresponding integer
return value is undefined.
GL_DIFFUSE params returns four integer or floating-point values
representing the diffuse intensity of the light source.
Integer values, when requested, are linearly mapped
from the internal floating-point representation such
that 1.0 maps to the most positive representable
integer value, and -1.0 maps to the most negative
representable integer value. If the internal value is
outside the range [-1,1], the corresponding integer
return value is undefined.
GL_SPECULAR params returns four integer or floating-point values
representing the specular intensity of the light
source. Integer values, when requested, are linearly
mapped from the internal floating-point representation
such that 1.0 maps to the most positive representable
integer value, and -1.0 maps to the most negative
representable integer value. If the internal value is
outside the range [-1,1], the corresponding integer
return value is undefined.
GL_POSITION params returns four integer or floating-point values
representing the position of the light source. Integer
values, when requested, are computed by rounding the
internal floating-point values to the nearest integer
value. The returned values are those maintained in eye
coordinates. They will not be equal to the values
specified using glLight, unless the modelview matrix
was identity at the time glLight was called.
GL_SPOT_DIRECTION params returns three integer or floating-point values
representing the direction of the light source.
Integer values, when requested, are computed by
rounding the internal floating-point values to the
nearest integer value. The returned values are those
maintained in eye coordinates. They will not be equal
to the values specified using glLight, unless the
modelview matrix was identity at the time glLight was
called. Although spot direction is normalized before
being used in the lighting equation, the returned
values are the transformed versions of the specified
values prior to normalization.
GL_SPOT_EXPONENT params returns a single integer or floating-point value
representing the spot exponent of the light. An
integer value, when requested, is computed by rounding
the internal floating-point representation to the
nearest integer.
GL_SPOT_CUTOFF params returns a single integer or floating-point value
representing the spot cutoff angle of the light. An
integer value, when requested, is computed by rounding
the internal floating-point representation to the
nearest integer.
GL_CONSTANT_ATTENUATION
params returns a single integer or floating-point value
representing the constant (not distance related)
attenuation of the light. An integer value, when
requested, is computed by rounding the internal
floating-point representation to the nearest integer.
GL_LINEAR_ATTENUATION
params returns a single integer or floating-point value
representing the linear attenuation of the light. An
integer value, when requested, is computed by rounding
the internal floating-point representation to the
nearest integer.
GL_QUADRATIC_ATTENUATION
params returns a single integer or floating-point value
representing the quadratic attenuation of the light.
An integer value, when requested, is computed by
rounding the internal floating-point representation to
the nearest integer.
Notes
It is always the case that GL_LIGHTi = GL_LIGHT0 + i.
If an error is generated, no change is made to the contents of params.
Errors
GL_INVALID_ENUM is generated if light or pname is not an accepted value.
GL_INVALID_OPERATION is generated if glGetLight is called between a call to
glBegin and the corresponding call to glEnd.
See Also
glLight
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ΓòÉΓòÉΓòÉ 3.46. glGetMap ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetMap
Name
glGetMapdv, glGetMapfv, glGetMapiv - return evaluator parameters
C Specification
void glGetMapdv( GLenum target,
GLenum query,
GLdouble *v )
void glGetMapfv( GLenum target,
GLenum query,
GLfloat *v )
void glGetMapiv( GLenum target,
GLenum query,
GLint *v )
Parameters
target Specifies the symbolic name of a map. Accepted values are
GL_MAP1_COLOR_4, GL_MAP1_INDEX, GL_MAP1_NORMAL,
GL_MAP1_TEXTURE_COORD_1, GL_MAP1_TEXTURE_COORD_2,
GL_MAP1_TEXTURE_COORD_3, GL_MAP1_TEXTURE_COORD_4, GL_MAP1_VERTEX_3,
GL_MAP1_VERTEX_4, GL_MAP2_COLOR_4 , GL_MAP2_INDEX, GL_MAP2_NORMAL,
GL_MAP2_TEXTURE_COORD_1, GL_MAP2_TEXTURE_COORD_2,
GL_MAP2_TEXTURE_COORD_3, GL_MAP2_TEXTURE_COORD_4, GL_MAP2_VERTEX_3,
and GL_MAP2_VERTEX_4.
query Specifies which parameter to return. Symbolic names GL_COEFF,
GL_ORDER, and GL_DOMAIN are accepted.
v Returns the requested data.
Description
glMap1 and glMap2 define evaluators. glGetMap returns evaluator
parameters. target chooses a map, query selects a specific parameter, and
v points to storage where the values will be returned.
The acceptable values for the target parameter are described in the glMap1
and glMap2 reference pages.
query can assume the following values:
GL_COEFF v returns the control points for the evaluator function.
One-dimensional evaluators return order control points,
and two-dimensional evaluators return uorderxvorder
control points. Each control point consists of one, two,
three, or four integer, single-precision floating-point,
or double-precision floating-point values, depending on
the type of the evaluator. Two-dimensional control
points are returned in row-major order, incrementing the
uorder index quickly, and the vorder index after each
row. Integer values, when requested, are computed by
rounding the internal floating-point values to the
nearest integer values.
GL_ORDER v returns the order of the evaluator function. One-
dimensional evaluators return a single value, order.
Two-dimensional evaluators return two values, uorder and
vorder.
GL_DOMAIN v returns the linear u and v mapping parameters. One-
dimensional evaluators return two values, u1 and u2, as
specified by glMap1. Two-dimensional evaluators return
four values (u1, u2, v1, and v2) as specified by glMap2.
Integer values, when requested, are computed by rounding
the internal floating-point values to the nearest integer
values.
Notes
If an error is generated, no change is made to the contents of v.
Errors
GL_INVALID_ENUM is generated if either target or query is not an accepted
value.
GL_INVALID_OPERATION is generated if glGetMap is called between a call to
glBegin and the corresponding call to glEnd.
See Also
glEvalCoord, glMap1, glMap2
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ΓòÉΓòÉΓòÉ 3.47. glGetMaterial ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetMaterial
Name
glGetMaterialfv, glGetMaterialiv - return material parameters
C Specification
void glGetMaterialfv( GLenum face,
GLenum pname,
GLfloat *params )
void glGetMaterialiv( GLenum face,
GLenum pname,
GLint *params )
Parameters
face Specifies which of the two materials is being queried. GL_FRONT or
GL_BACK are accepted, representing the front and back materials,
respectively.
pname Specifies the material parameter to return. GL_AMBIENT,
GL_DIFFUSE, GL_SPECULAR, GL_EMISSION, GL_SHININESS, and
GL_COLOR_INDEXES are accepted.
params Returns the requested data.
Description
glGetMaterial returns in params the value or values of parameter pname of
material face. Six parameters are defined:
GL_AMBIENT params returns four integer or floating-point values
representing the ambient reflectance of the material.
Integer values, when requested, are linearly mapped
from the internal floating-point representation such
that 1.0 maps to the most positive representable
integer value, and -1.0 maps to the most negative
representable integer value. If the internal value is
outside the range [-1,1], the corresponding integer
return value is undefined.
GL_DIFFUSE params returns four integer or floating-point values
representing the diffuse reflectance of the material.
Integer values, when requested, are linearly mapped
from the internal floating-point representation such
that 1.0 maps to the most positive representable
integer value, and -1.0 maps to the most negative
representable integer value. If the internal value is
outside the range [-1,1], the corresponding integer
return value is undefined.
GL_SPECULAR params returns four integer or floating-point values
representing the specular reflectance of the material.
Integer values, when requested, are linearly mapped
from the internal floating-point representation such
that 1.0 maps to the most positive representable
integer value, and -1.0 maps to the most negative
representable integer value. If the internal value is
outside the range [-1,1], the corresponding integer
return value is undefined.
GL_EMISSION params returns four integer or floating-point values
representing the emitted light intensity of the
material. Integer values, when requested, are linearly
mapped from the internal floating-point representation
such that 1.0 maps to the most positive representable
integer value, and -1.0 maps to the most negative
representable integer value. If the internal value is
outside the range [-1,1], the corresponding integer
return value is undefined.
GL_SHININESS params returns one integer or floating-point value
representing the specular exponent of the material.
Integer values, when requested, are computed by
rounding the internal floating-point value to the
nearest integer value.
GL_COLOR_INDEXES params returns three integer or floating-point values
representing the ambient, diffuse, and specular indices
of the material. These indices are used only for color
index lighting. (The other parameters are all used
only for RGBA lighting.) Integer values, when
requested, are computed by rounding the internal
floating-point values to the nearest integer values.
Notes
If an error is generated, no change is made to the contents of params.
Errors
GL_INVALID_ENUM is generated if face or pname is not an accepted value.
GL_INVALID_OPERATION is generated if glGetMaterial is called between a call
to glBegin and the corresponding call to glEnd.
See Also
glMaterial
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ΓòÉΓòÉΓòÉ 3.48. glGetPixelMap ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetPixelMap
Name
glGetPixelMapfv, glGetPixelMapuiv, glGetPixelMapusv - return the specified
pixel map
C Specification
void glGetPixelMapfv( GLenum map,
GLfloat *values )
void glGetPixelMapuiv( GLenum map,
GLuint *values )
void glGetPixelMapusv( GLenum map,
GLushort *values )
Parameters
map Specifies the name of the pixel map to return. Accepted values are
GL_PIXEL_MAP_I_TO_I, GL_PIXEL_MAP_S_TO_S, GL_PIXEL_MAP_I_TO_R,
GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B, GL_PIXEL_MAP_I_TO_A,
GL_PIXEL_MAP_R_TO_R, GL_PIXEL_MAP_G_TO_G, GL_PIXEL_MAP_B_TO_B, and
GL_PIXEL_MAP_A_TO_A.
values Returns the pixel map contents.
Description
Please see the glPixelMap reference page for a description of the
acceptable values for the map parameter. glGetPixelMap returns in values
the contents of the pixel map specified in map. Pixel maps are used during
the execution of glReadPixels, glDrawPixels, glCopyPixels, glTexImage1D,
and glTexImage2D to map color indices, stencil indices, color components,
and depth components to other values.
Unsigned integer values, if requested, are linearly mapped from the
internal fixed or floating-point representation such that 1.0 maps to the
largest representable integer value, and 0.0 maps to zero. Return unsigned
integer values are undefined if the map value was not in the range [0,1].
To determine the required size of map, call glGet with the appropriate
symbolic constant.
Notes
If an error is generated, no change is made to the contents of values.
Errors
GL_INVALID_ENUM is generated if map is not an accepted value.
GL_INVALID_OPERATION is generated if glGetPixelMap is called between a call
to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_PIXEL_MAP_I_TO_I_SIZE
glGet with argument GL_PIXEL_MAP_S_TO_S_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_R_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_G_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_B_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_A_SIZE
glGet with argument GL_PIXEL_MAP_R_TO_R_SIZE
glGet with argument GL_PIXEL_MAP_G_TO_G_SIZE
glGet with argument GL_PIXEL_MAP_B_TO_B_SIZE
glGet with argument GL_PIXEL_MAP_A_TO_A_SIZE
glGet with argument GL_MAX_PIXEL_MAP_TABLE
See Also
glCopyPixels, glDrawPixels, glPixelMap, glPixelTransfer, glReadPixels,
glTexImage1D, glTexImage2D
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ΓòÉΓòÉΓòÉ 3.49. glGetPointervEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetPointervEXT
Name
glGetPointervEXT - return the address of a vertex data array
C Specification
void glGetPointervEXT( GLenum pname,
GLvoid* *params )
Parameters
pname Specifies the array pointer to be returned. Symbolic constants
GL_VERTEX_ARRAY_POINTER_EXT, GL_NORMAL_ARRAY_POINTER_EXT,
GL_COLOR_ARRAY_POINTER_EXT, GL_INDEX_ARRAY_POINTER_EXT,
GL_TEXTURE_COORD_ARRAY_POINTER_EXT, GL_EDGE_FLAG_ARRAY_POINTER_EXT,
are accepted.
params returns the array pointer value specified by pname.
Description
glGetPointervEXT returns array pointer information. pname is a symbolic
constant indicating the array pointer to be returned, and params is a
pointer to a location in which to place the returned data.
Notes
The array pointers are client side state.
glGetPointervEXT is part of the EXT_vertex_array extension, not
part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
Errors
GL_INVALID_ENUM is generated if pname is not an accepted value.
See Also
glArrayElementEXT, glColorPointerEXT, glDrawArraysEXT,
glEdgeFlagPointerEXT, glIndexPointerEXT, glNormalPointerEXT,
glTexCoordPointerEXT, glVertexPointerEXT
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ΓòÉΓòÉΓòÉ 3.50. glGetPolygonStipple ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetPolygonStipple
Name
glGetPolygonStipple - return the polygon stipple pattern
C Specification
void glGetPolygonStipple( GLubyte *mask )
Parameters
mask Returns the stipple pattern.
Description
glGetPolygonStipple returns to mask a 32x32 polygon stipple pattern. The
pattern is packed into memory as if glReadPixels with both height and width
of 32, type of GL_BITMAP, and format of GL_COLOR_INDEX were called, and the
stipple pattern were stored in an internal 32x32 color index buffer.
Unlike glReadPixels, however, pixel transfer operations (shift, offset,
pixel map) are not applied to the returned stipple image.
Notes
If an error is generated, no change is made to the contents of mask.
Errors
GL_INVALID_OPERATION is generated if glGetPolygonStipple is executed
between the execution of glBegin and the corresponding execution of glEnd.
See Also
glPixelStore, glPixelTransfer, glPolygonStipple, glReadPixels
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ΓòÉΓòÉΓòÉ 3.51. glGetString ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetString
Name
glGetString - returns a string describing the current GL connection
C Specification
const GLubyte * glGetString( GLenum name )
Parameters
name Specifies a symbolic constant, one of GL_VENDOR, GL_RENDERER,
GL_VERSION, or GL_EXTENSIONS.
Description
glGetString returns a pointer to a static string describing some aspect of
the current GL connection. name can be one of the following:
GL_VENDOR Returns the company responsible for this GL
implementation. This name does not change from release
to release.
GL_RENDERER Returns the name of the renderer. This name is
typically specific to a particular configuration of a
hardware platform. It does not change from release to
release.
GL_VERSION Returns a version or release number.
GL_EXTENSIONS Returns a space-separated list of supported extensions
to GL.
Because GL does not include queries for the performance characteristics of
an implementation, it is expected that some applications will be written to
recognize known platforms and will modify their GL usage based on known
performance characteristics of these platforms. Strings GL_VENDOR and
GL_RENDERER together uniquely specify a platform, and will not change from
release to release. They should be used by such platform recognition
algorithms.
Some applications will want to make use of features which are not part of
the standard GL. These features may be implemented as extensions to the
standard GL. The GL_EXTENSIONS string is a space seperated list of
supported GL extensions. (Extension names never contain a space character.)
The GL_VERSION string begins with a version number. The version number is
of the form major_number.minor_number or
major_number.minor_number.release_number. Vendor specific information may
follow the version number. Its format depends on the implementation, but a
space always seperates the version number and the vendor specific
information.
All strings are null-terminated.
Notes
If an error is generated, glGetString returns zero.
The client and server may support different versions or extensions.
glGetString always returns a compatible version number or list of
extensions. The release number always describes the server.
Errors
GL_INVALID_ENUM is generated if name is not an accepted value.
GL_INVALID_OPERATION is generated if glGetString is executed between the
execution of glBegin and the corresponding execution of glEnd.
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.52. glGetTexEnv ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetTexEnv
Name
glGetTexEnvfv, glGetTexEnviv - return texture environment parameters
C Specification
void glGetTexEnvfv( GLenum target,
GLenum pname,
GLfloat *params )
void glGetTexEnviv( GLenum target,
GLenum pname,
GLint *params )
Parameters
target Specifies a texture environment. Must be GL_TEXTURE_ENV.
pname Specifies the symbolic name of a texture environment parameter.
Accepted values are GL_TEXTURE_ENV_MODE and GL_TEXTURE_ENV_COLOR.
params Returns the requested data.
Description
glGetTexEnv returns in params selected values of a texture environment that
was specified with glTexEnv. target specifies a texture environment.
Currently, only one texture environment is defined and supported:
GL_TEXTURE_ENV.
pname names a specific texture environment parameter. The two parameters
are as follows:
GL_TEXTURE_ENV_MODE
params returns the single-valued texture environment mode, a
symbolic constant.
GL_TEXTURE_ENV_COLOR
params returns four integer or floating-point values that are the
texture environment color. Integer values, when requested, are
linearly mapped from the internal floating-point representation
such that 1.0 maps to the most positive representable integer,
and -1.0 maps to the most negative representable integer.
Notes
If an error is generated, no change is made to the contents of params.
Errors
GL_INVALID_ENUM is generated if target or pname is not an accepted value.
GL_INVALID_OPERATION is generated if glGetTexEnv is called between a call
to glBegin and the corresponding call to glEnd.
See Also
glTexEnv
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ΓòÉΓòÉΓòÉ 3.53. glGetTexGen ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetTexGen
Name
glGetTexGendv, glGetTexGenfv, glGetTexGeniv - return texture coordinate
generation parameters
C Specification
void glGetTexGendv( GLenum coord,
GLenum pname,
GLdouble *params )
void glGetTexGenfv( GLenum coord,
GLenum pname,
GLfloat *params )
void glGetTexGeniv( GLenum coord,
GLenum pname,
GLint *params )
Parameters
coord Specifies a texture coordinate. Must be GL_S, GL_T, GL_R, or GL_Q.
pname Specifies the symbolic name of the value(s) to be returned. Must
be either GL_TEXTURE_GEN_MODE or the name of one of the texture
generation plane equations: GL_OBJECT_PLANE or GL_EYE_PLANE.
params Returns the requested data.
Description
glGetTexGen returns in params selected parameters of a texture coordinate
generation function that was specified using glTexGen. coord names one of
the (s,t,r,q) texture coordinates, using the symbolic constant GL_S, GL_T,
GL_R, or GL_Q.
pname specifies one of three symbolic names:
GL_TEXTURE_GEN_MODE params returns the single-valued texture
generation function, a symbolic constant.
GL_OBJECT_PLANE params returns the four plane equation
coefficients that specify object linear-
coordinate generation. Integer values, when
requested, are mapped directly from the
internal floating-point representation.
GL_EYE_PLANE params returns the four plane equation
coefficients that specify eye linear-
coordinate generation. Integer values, when
requested, are mapped directly from the
internal floating-point representation. The
returned values are those maintained in eye
coordinates. They are not equal to the
values specified using glTexGen, unless the
modelview matrix was identity at the time
glTexGen was called.
Notes
If an error is generated, no change is made to the contents of params.
Errors
GL_INVALID_ENUM is generated if coord or pname is not an accepted value.
GL_INVALID_OPERATION is generated if glGetTexGen is called between a call
to glBegin and the corresponding call to glEnd.
See Also
glTexGen
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ΓòÉΓòÉΓòÉ 3.54. glGetTexImage ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetTexImage
Name
glGetTexImage - return a texture image
C Specification
void glGetTexImage( GLenum target,
GLint level,
GLenum format,
GLenum type,
GLvoid *pixels )
Parameters
target Specifies which texture is to be obtained. GL_TEXTURE_1D and
GL_TEXTURE_2D are accepted.
level Specifies the level-of-detail number of the desired image. Level 0
is the base image level. Level n is the nth mipmap reduction
image.
format Specifies a pixel format for the returned data. The supported
formats are GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA,
GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
type Specifies a pixel type for the returned data. The supported types
are GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT,
GL_UNSIGNED_INT, GL_INT, and GL_FLOAT.
pixels Returns the texture image. Should be a pointer to an array of the
type specified by type.
Description
glGetTexImage returns a texture image into pixels. target specifies
whether the desired texture image is one specified by glTexImage1D
(GL_TEXTURE_1D) or by glTexImage2D (GL_TEXTURE_2D). level specifies the
level-of-detail number of the desired image. format and type specify the
format and type of the desired image array. Please see the reference pages
glTexImage1D and glDrawPixels for a description of the acceptable values
for the format and type parameters, respectively.
Operation of glGetTexImage is best understood by considering the selected
internal four-component texture image to be an RGBA color buffer the size
of the image. The semantics of glGetTexImage are then identical to those
of glReadPixels called with the same format and type, with x and y set to
zero, width set to the width of the texture image (including border if one
was specified), and height set to one for 1-D images, or to the height of
the texture image (including border if one was specified) for 2-D images.
Because the internal texture image is an RGBA image, pixel formats
GL_COLOR_INDEX, GL_STENCIL_INDEX, and GL_DEPTH_COMPONENT are not accepted,
and pixel type GL_BITMAP is not accepted.
If the selected texture image does not contain four components, the
following mappings are applied. Single-component textures are treated as
RGBA buffers with red set to the single-component value, and green, blue,
and alpha set to zero. Two-component textures are treated as RGBA buffers
with red set to the value of component zero, alpha set to the value of
component one, and green and blue set to zero. Finally, three-component
textures are treated as RGBA buffers with red set to component zero, green
set to component one, blue set to component two, and alpha set to zero.
To determine the required size of pixels, use glGetTexLevelParameter to
ascertain the dimensions of the internal texture image, then scale the
required number of pixels by the storage required for each pixel, based on
format and type. Be sure to take the pixel storage parameters into
account, especially GL_PACK_ALIGNMENT.
Notes
If an error is generated, no change is made to the contents of pixels.
Errors
GL_INVALID_ENUM is generated if target, format, or type is not an accepted
value.
GL_INVALID_VALUE is generated if level is less than zero or greater than
log max, where max is the returned value of GL_MAX_TEXTURE_SIZE.
2
GL_INVALID_OPERATION is generated if glGetTexImage is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetTexLevelParameter with argument GL_TEXTURE_WIDTH
glGetTexLevelParameter with argument GL_TEXTURE_HEIGHT
glGetTexLevelParameter with argument GL_TEXTURE_BORDER
glGetTexLevelParameter with argument GL_TEXTURE_COMPONENTS
glGet with arguments GL_PACK_ALIGNMENT and others
See Also
glDrawPixels, glReadPixels, glTexImage1D, glTexImage2D
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ΓòÉΓòÉΓòÉ 3.55. glGetTexLevelParameter ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetTexLevelParameter
Name
glGetTexLevelParameterfv, glGetTexLevelParameteriv - return texture
parameter values for a specific level of detail
C Specification
void glGetTexLevelParameterfv( GLenum target,
GLint level,
GLenum pname,
GLfloat *params )
void glGetTexLevelParameteriv( GLenum target,
GLint level,
GLenum pname,
GLint *params )
Parameters
target Specifies the symbolic name of the target texture, either
GL_TEXTURE_1D or GL_TEXTURE_2D.
level Specifies the level-of-detail number of the desired image. Level 0
is the base image level. Level n is the nth mipmap reduction
image.
pname Specifies the symbolic name of a texture parameter.
GL_TEXTURE_WIDTH, GL_TEXTURE_HEIGHT, GL_TEXTURE_COMPONENTS, and
GL_TEXTURE_BORDER are accepted.
params Returns the requested data.
Description
glGetTexLevelParameter returns in params texture parameter values for a
specific level-of-detail value, specified as level. target defines the
target texture, either GL_TEXTURE_1D or GL_TEXTURE_2D, to specify one- or
two-dimensional texturing. pname specifies the texture parameter whose
value or values will be returned.
The accepted parameter names are as follows:
GL_TEXTURE_WIDTH
params returns a single value, the width of the texture image.
This value includes the border of the texture image.
GL_TEXTURE_HEIGHT
params returns a single value, the height of the texture image.
This value includes the border of the texture image.
GL_TEXTURE_COMPONENTS
params returns a single value, the number of components in the
texture image.
GL_TEXTURE_BORDER
params returns a single value, the width in pixels of the border
of the texture image.
Notes
If an error is generated, no change is made to the contents of params.
Errors
GL_INVALID_ENUM is generated if target or pname is not an accepted value.
GL_INVALID_VALUE is generated if level is less than zero or greater than
log max, where max is the returned value of GL_MAX_TEXTURE_SIZE.
2
GL_INVALID_OPERATION is generated if glGetTexLevelParameter is called
between a call to glBegin and the corresponding call to glEnd.
See Also
glGetTexParameter, glTexImage1D, glTexImage2D, glTexParameter
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ΓòÉΓòÉΓòÉ 3.56. glGetTexParameter ΓòÉΓòÉΓòÉ
OpenGL man pages
glGetTexParameter
Name
glGetTexParameterfv, glGetTexParameteriv - return texture parameter values
C Specification
void glGetTexParameterfv( GLenum target,
GLenum pname,
GLfloat *params )
void glGetTexParameteriv( GLenum target,
GLenum pname,
GLint *params )
Parameters
target Specifies the symbolic name of the target texture. GL_TEXTURE_1D
and GL_TEXTURE_2D are accepted.
pname Specifies the symbolic name of a texture parameter.
GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_FILTER, GL_TEXTURE_WRAP_S,
GL_TEXTURE_WRAP_T, and GL_TEXTURE_BORDER_COLOR are accepted.
params Returns the texture parameters.
Description
glGetTexParameter returns in params the value or values of the texture
parameter specified as pname. target defines the target texture, either
GL_TEXTURE_1D or GL_TEXTURE_2D, to specify one- or two-dimensional
texturing. pname accepts the same symbols as glTexParameter, with the same
interpretations:
GL_TEXTURE_MAG_FILTER Returns the single-valued texture
magnification filter, a symbolic
constant.
GL_TEXTURE_MIN_FILTER Returns the single-valued texture
minification filter, a symbolic
constant.
GL_TEXTURE_WRAP_S Returns the single-valued wrapping
function for texture coordinate s, a
symbolic constant.
GL_TEXTURE_WRAP_T Returns the single-valued wrapping
function for texture coordinate t, a
symbolic constant.
GL_TEXTURE_BORDER_COLOR Returns four integer or floating-point
numbers that comprise the RGBA color of
the texture border. Floating-point
values are returned in the range [0,1].
Integer values are returned as a linear
mapping of the internal floating-point
representation such that 1.0 maps to the
most positive representable integer and
-1.0 maps to the most negative
representable integer.
Notes
If an error is generated, no change is made to the contents of params.
Errors
GL_INVALID_ENUM is generated if target or pname is not an accepted value.
GL_INVALID_OPERATION is generated if glGetTexParameter is called between a
call to glBegin and the corresponding call to glEnd.
See Also
glTexParameter
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ΓòÉΓòÉΓòÉ 3.57. glHint ΓòÉΓòÉΓòÉ
OpenGL man pages
glHint
Name
glHint - specify implementation-specific hints
C Specification
void glHint( GLenum target,
GLenum mode )
Parameters
target Specifies a symbolic constant indicating the behavior to be
controlled. GL_FOG_HINT, GL_LINE_SMOOTH_HINT,
GL_PERSPECTIVE_CORRECTION_HINT, GL_POINT_SMOOTH_HINT, and
GL_POLYGON_SMOOTH_HINT are accepted.
mode Specifies a symbolic constant indicating the desired behavior.
GL_FASTEST, GL_NICEST, and GL_DONT_CARE are accepted.
Description
Certain aspects of GL behavior, when there is room for interpretation, can
be controlled with hints. A hint is specified with two arguments. target
is a symbolic constant indicating the behavior to be controlled, and mode
is another symbolic constant indicating the desired behavior. mode can be
one of the following:
GL_FASTEST The most efficient option should be chosen.
GL_NICEST The most correct, or highest quality, option should be
chosen.
GL_DONT_CARE The client doesn't have a preference.
Though the implementation aspects that can be hinted are well defined, the
interpretation of the hints depends on the implementation. The hint
aspects that can be specified with target, along with suggested semantics,
are as follows:
GL_FOG_HINT Indicates the accuracy of fog calculation. If per-
pixel fog calculation is not efficiently supported by
the GL implementation, hinting GL_DONT_CARE or
GL_FASTEST can result in per-vertex calculation of fog
effects.
GL_LINE_SMOOTH_HINT Indicates the sampling quality of antialiased lines.
Hinting GL_NICEST can result in more pixel fragments
being generated during rasterization, if a larger
filter function is applied.
GL_PERSPECTIVE_CORRECTION_HINT
Indicates the quality of color and texture coordinate
interpolation. If perspective-corrected parameter
interpolation is not efficiently supported by the GL
implementation, hinting GL_DONT_CARE or GL_FASTEST can
result in simple linear interpolation of colors and/or
texture coordinates.
GL_POINT_SMOOTH_HINT
Indicates the sampling quality of antialiased points.
Hinting GL_NICEST can result in more pixel fragments
being generated during rasterization, if a larger
filter function is applied.
GL_POLYGON_SMOOTH_HINT
Indicates the sampling quality of antialiased polygons.
Hinting GL_NICEST can result in more pixel fragments
being generated during rasterization, if a larger
filter function is applied.
Notes
The interpretation of hints depends on the implementation. glHint can be
ignored.
Errors
GL_INVALID_ENUM is generated if either target or mode is not an accepted
value.
GL_INVALID_OPERATION is generated if glHint is executed between the
execution of glBegin and the corresponding execution of glEnd.
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ΓòÉΓòÉΓòÉ 3.58. glIndex ΓòÉΓòÉΓòÉ
OpenGL man pages
glIndex
Name
glIndexd, glIndexf, glIndexi, glIndexs, glIndexdv,
glIndexfv, glIndexiv,
glIndexsv - set the current color index
C Specification
void glIndexd( GLdouble c )
void glIndexf( GLfloat c )
void glIndexi( GLint c )
void glIndexs( GLshort c )
Parameters
c Specifies the new value for the current color index.
C Specification
void glIndexdv( const GLdouble *c )
void glIndexfv( const GLfloat *c )
void glIndexiv( const GLint *c )
void glIndexsv( const GLshort *c )
Parameters
c Specifies a pointer to a one-element array that contains the new value
for the current color index.
Description
glIndex updates the current (single-valued) color index. It takes one
argument: the new value for the current color index.
The current index is stored as a floating-point value. Integer values are
converted directly to floating-point values, with no special mapping.
Index values outside the representable range of the color index buffer are
not clamped. However, before an index is dithered (if enabled) and written
to the frame buffer, it is converted to fixed-point format. Any bits in
the integer portion of the resulting fixed-point value that do not
correspond to bits in the frame buffer are masked out.
Notes
The current index can be updated at any time. In particular, glIndex can
be called between a call to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_CURRENT_INDEX
See Also
glColor
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ΓòÉΓòÉΓòÉ 3.59. glIndexMask ΓòÉΓòÉΓòÉ
OpenGL man pages
glIndexMask
Name
glIndexMask - control the writing of individual bits in the color index
buffers
C Specification
void glIndexMask( GLuint mask )
Parameters
mask Specifies a bit mask to enable and disable the writing of individual
bits in the color index buffers. Initially, the mask is all ones.
Description
glIndexMask controls the writing of individual bits in the color index
buffers. The least significant n bits of mask, where n is the number of
bits in a color index buffer, specify a mask. Wherever a one appears in
the mask, the corresponding bit in the color index buffer (or buffers) is
made writable. Where a zero appears, the bit is write-protected.
This mask is used only in color index mode, and it affects only the buffers
currently selected for writing (see glDrawBuffer). Initially, all bits are
enabled for writing.
Errors
GL_INVALID_OPERATION is generated if glIndexMask is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_INDEX_WRITEMASK
See Also
glColorMask, glDepthMask, glDrawBuffer, glIndex, glStencilMask
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ΓòÉΓòÉΓòÉ 3.60. glIndexPointerEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glIndexPointerEXT
Name
glIndexPointerEXT - define an array of color indexes
C Specification
void glIndexPointerEXT( GLenum type,
GLsizei stride,
GLsizei count,
const GLvoid *pointer )
Parameters
type Specifies the data type of each color index in the array.
Symbolic constants GL_SHORT, GL_INT, GL_FLOAT, or GL_DOUBLE_EXT,
are accepted.
stride Specifies the byte offset between consecutive color indexes. If
stride is zero the color indexes are understood to be tightly
packed in the array.
count Specifies the number of indexes, counting from the first, that are
static.
pointer Specifies a pointer to the first index in the array.
Description
glIndexPointerEXT specifies the location and data format of an array of
color indexes to use when rendering using the vertex array extension. type
specifies the data type of each color index and stride gives the byte
stride from one color index to the next allowing vertexes and attributes to
be packed into a single array or stored in separate arrays. (Single-array
storage may be more efficient on some implementations.) count indicates
the number of array elements (counting from the first) that are static.
Static elements may be modified by the application, but once they are
modified, the application must explicitly respecify the array before using
it for any rendering. When a color index array is specified, type, stride,
count and pointer are saved as client-side state, and static array elements
may be cached by the implementation.
The color index array is enabled and disabled using glEnable and glDisable
with the argument GL_INDEX_ARRAY_EXT. If enabled, the color index array is
used when glDrawArraysEXT or glArrayElementEXT is called.
Use glDrawArraysEXT to define a sequence of primitives (all of the same
type) from pre-specified vertex and vertex attribute arrays. Use
glArrayElementEXT to specify primitives by indexing vertexes and vertex
attributes.
Notes
Non-static array elements are not accessed until glArrayElementEXT or
glDrawArraysEXT is executed.
By default the color index array is disabled and it won't be accessed when
glArrayElementEXT or glDrawArraysEXT is called.
Although it is not an error to call glIndexPointerEXT between the
execution of glBegin and the corresponding execution of glEnd, the results
are undefined.
glIndexPointerEXT will typically be implemented on the client side with no
protocol.
Since the color index array parameters are client side state, they are not
saved or restored by glPushAttrib and glPopAttrib.
glIndexPointerEXT commands are not entered into display lists.
glIndexPointerEXT is part of the EXT_vertex_array extension, not
part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
Errors
GL_INVALID_ENUM is generated if type is not an accepted value.
GL_INVALID_VALUE is generated if stride or count is negative.
Associated Gets
glIsEnabled with argument GL_INDEX_ARRAY_EXT
glGet with argument GL_INDEX_ARRAY_SIZE_EXT
glGet with argument GL_INDEX_ARRAY_TYPE_EXT
glGet with argument GL_INDEX_ARRAY_STRIDE_EXT
glGet with argument GL_INDEX_ARRAY_COUNT_EXT
glGetPointervEXT with argument GL_INDEX_ARRAY_POINTER_EXT
See Also
glArrayElementEXT, glColorPointerEXT, glDrawArraysEXT,
glEdgeFlagPointerEXT, glGetPointervEXT, glNormalPointerEXT,
glTexCoordPointerEXT, glVertexPointerEXT, glEnable
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ΓòÉΓòÉΓòÉ 3.61. glInitNames ΓòÉΓòÉΓòÉ
OpenGL man pages
glInitNames
Name
glInitNames - initialize the name stack
C Specification
void glInitNames( void )
Description
The name stack is used during selection mode to allow sets of rendering
commands to be uniquely identified. It consists of an ordered set of
unsigned integers. glInitNames causes the name stack to be initialized to
its default empty state.
The name stack is always empty while the render mode is not GL_SELECT.
Calls to glInitNames while the render mode is not GL_SELECT are ignored.
Errors
GL_INVALID_OPERATION is generated if glInitNames is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_NAME_STACK_DEPTH
glGet with argument GL_MAX_NAME_STACK_DEPTH
See Also
glLoadName, glPushName, glRenderMode, glSelectBuffer
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ΓòÉΓòÉΓòÉ 3.62. glIsEnabled ΓòÉΓòÉΓòÉ
OpenGL man pages
glIsEnabled
Name
glIsEnabled - test whether a capability is enabled
C Specification
GLboolean glIsEnabled( GLenum cap )
Parameters
cap Specifies a symbolic constant indicating a GL capability.
Description
glIsEnabled returns GL_TRUE if cap is an enabled capability and returns
GL_FALSE otherwise. The following capabilities are accepted for cap:
GL_ALPHA_TEST See glAlphaFunc.
GL_AUTO_NORMAL See glEvalCoord.
GL_BLEND See glBlendFunc.
GL_CLIP_PLANEi See glClipPlane.
GL_COLOR_ARRAY_EXT See glColorPointerEXT.
GL_COLOR_MATERIAL See glColorMaterial.
GL_CULL_FACE See glCullFace.
GL_DEPTH_TEST See glDepthFunc and glDepthRange.
GL_DITHER See glEnable.
GL_EDGE_FLAG_ARRAY_EXT See glEdgeFlagPointerEXT.
GL_FOG See glFog.
GL_INDEX_ARRAY_EXT See glIndexPointerEXT.
GL_LIGHTi See glLightModel and glLight.
GL_LIGHTING See glMaterial, glLightModel, and glLight.
GL_LINE_SMOOTH See glLineWidth.
GL_LINE_STIPPLE See glLineStipple.
GL_LOGIC_OP See glLogicOp.
GL_MAP1_COLOR_4 See glMap1.
GL_MAP1_INDEX See glMap1.
GL_MAP1_NORMAL See glMap1.
GL_MAP1_TEXTURE_COORD_1 See glMap1.
GL_MAP1_TEXTURE_COORD_2 See glMap1.
GL_MAP1_TEXTURE_COORD_3 See glMap1.
GL_MAP1_TEXTURE_COORD_4 See glMap1.
GL_MAP1_VERTEX_3 See glMap1.
GL_MAP1_VERTEX_4 See glMap1.
GL_MAP2_COLOR_4 See glMap2.
GL_MAP2_INDEX See glMap2.
GL_MAP2_NORMAL See glMap2.
GL_MAP2_TEXTURE_COORD_1 See glMap2.
GL_MAP2_TEXTURE_COORD_2 See glMap2.
GL_MAP2_TEXTURE_COORD_3 See glMap2.
GL_MAP2_TEXTURE_COORD_4 See glMap2.
GL_MAP2_VERTEX_3 See glMap2.
GL_MAP2_VERTEX_4 See glMap2.
GL_NORMAL_ARRAY_EXT See glNormalPointerEXT.
GL_NORMALIZE See glNormal.
GL_POINT_SMOOTH See glPointSize.
GL_POLYGON_SMOOTH See glPolygonMode.
GL_POLYGON_STIPPLE See glPolygonStipple.
GL_SCISSOR_TEST See glScissor.
GL_STENCIL_TEST See glStencilFunc and glStencilOp.
GL_TEXTURE_1D See glTexImage1D.
GL_TEXTURE_2D See glTexImage2D.
GL_TEXTURE_COORD_ARRAY_EXT See glTexCoordPointerEXT.
GL_TEXTURE_GEN_Q See glTexGen.
GL_TEXTURE_GEN_R See glTexGen.
GL_TEXTURE_GEN_S See glTexGen.
GL_TEXTURE_GEN_T See glTexGen.
GL_VERTEX_ARRAY_EXT See glVertexPointerEXT.
Notes
If an error is generated, glIsEnabled returns zero.
Errors
GL_INVALID_ENUM is generated if cap is not an accepted value.
GL_INVALID_OPERATION is generated if glIsEnabled is executed between the
execution of glBegin and the corresponding execution of glEnd.
See Also
glEnable
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ΓòÉΓòÉΓòÉ 3.63. glIsList ΓòÉΓòÉΓòÉ
OpenGL man pages
glIsList
Name
glIsList - test for display-list existence
C Specification
GLboolean glIsList( GLuint list )
Parameters
list Specifies a potential display-list name.
Description
glIsList returns GL_TRUE if list is the name of a display list and returns
GL_FALSE otherwise.
Errors
GL_INVALID_OPERATION is generated if glIsList is executed between the
execution of glBegin and the corresponding execution of glEnd.
See Also
glCallList, glCallLists, glDeleteLists, glGenLists, glNewList
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ΓòÉΓòÉΓòÉ 3.64. glLight ΓòÉΓòÉΓòÉ
OpenGL man pages
glLight
Name
glLightf, glLighti, glLightfv, glLightiv - set light source parameters
C Specification
void glLightf( GLenum light,
GLenum pname,
GLfloat param )
void glLighti( GLenum light,
GLenum pname,
GLint param )
Parameters
light Specifies a light. The number of lights is depends on the
implementation, but at least eight lights are supported. They are
identified by symbolic names of the form GL_LIGHTi where 0 <= i <
GL_MAX_LIGHTS.
pname Specifies a single-valued light source parameter for light.
GL_SPOT_EXPONENT, GL_SPOT_CUTOFF, GL_CONSTANT_ATTENUATION,
GL_LINEAR_ATTENUATION , and GL_QUADRATIC_ATTENUATION are accepted.
param Specifies the value that parameter pname of light source light will
be set to.
C Specification
void glLightfv( GLenum light,
GLenum pname,
const GLfloat *params )
void glLightiv( GLenum light,
GLenum pname,
const GLint *params )
Parameters
light
Specifies a light. The number of lights depends on the
implementation, but at least eight lights are supported. They are
identified by symbolic names of the form GL_LIGHTi where 0 <= i <
GL_MAX_LIGHTS.
pname
Specifies a light source parameter for light. GL_AMBIENT, GL_DIFFUSE,
GL_SPECULAR, GL_POSITION, GL_SPOT_DIRECTION, GL_SPOT_EXPONENT,
GL_SPOT_CUTOFF, GL_CONSTANT_ATTENUATION, GL_LINEAR_ATTENUATION, and
GL_QUADRATIC_ATTENUATION are accepted.
params
Specifies a pointer to the value or values that parameter pname of
light source light will be set to.
Description
glLight sets the values of individual light source parameters. light names
the light and is a symbolic name of the form GL_LIGHTi, where 0 <= i <
GL_MAX_LIGHTS. pname specifies one of ten light source parameters, again
by symbolic name. params is either a single value or a pointer to an array
that contains the new values.
Lighting calculation is enabled and disabled using glEnable and glDisable
with argument GL_LIGHTING. When lighting is enabled, light sources that
are enabled contribute to the lighting calculation. Light source i is
enabled and disabled using glEnable and glDisable with argument GL_LIGHTi.
The ten light parameters are as follows:
GL_AMBIENT params contains four integer or floating-point values
that specify the ambient RGBA intensity of the light.
Integer values are mapped linearly such that the most
positive representable value maps to 1.0, and the most
negative representable value maps to -1.0. Floating-
point values are mapped directly. Neither integer nor
floating-point values are clamped. The default ambient
light intensity is (0.0, 0.0, 0.0, 1.0).
GL_DIFFUSE params contains four integer or floating-point values
that specify the diffuse RGBA intensity of the light.
Integer values are mapped linearly such that the most
positive representable value maps to 1.0, and the most
negative representable value maps to -1.0. Floating-
point values are mapped directly. Neither integer nor
floating-point values are clamped. The default diffuse
intensity is (0.0, 0.0, 0.0, 1.0) for all lights other
than light zero. The default diffuse intensity of
light zero is (1.0, 1.0, 1.0, 1.0).
GL_SPECULAR params contains four integer or floating-point values
that specify the specular RGBA intensity of the light.
Integer values are mapped linearly such that the most
positive representable value maps to 1.0, and the most
negative representable value maps to -1.0. Floating-
point values are mapped directly. Neither integer nor
floating-point values are clamped. The default
specular intensity is (0.0, 0.0, 0.0, 1.0) for all
lights other than light zero. The default specular
intensity of light zero is (1.0, 1.0, 1.0, 1.0).
GL_POSITION params contains four integer or floating-point values
that specify the position of the light in homogeneous
object coordinates. Both integer and floating-point
values are mapped directly. Neither integer nor
floating-point values are clamped.
The position is transformed by the modelview matrix
when glLight is called (just as if it were a point),
and it is stored in eye coordinates. If the w
component of the position is 0.0, the light is treated
as a directional source. Diffuse and specular lighting
calculations take the light's direction, but not its
actual position, into account, and attenuation is
disabled. Otherwise, diffuse and specular lighting
calculations are based on the actual location of the
light in eye coordinates, and attenuation is enabled.
The default position is (0,0,1,0); thus, the default
light source is directional, parallel to, and in the
direction of the -z axis.
GL_SPOT_DIRECTION params contains three integer or floating-point values
that specify the direction of the light in homogeneous
object coordinates. Both integer and floating-point
values are mapped directly. Neither integer nor
floating-point values are clamped.
The spot direction is transformed by the inverse of the
modelview matrix when glLight is called (just as it it
were a normal), and it is stored in eye coordinates.
It is significant only when GL_SPOT_CUTOFF is not 180,
which it is by default. The default direction is
(0,0,-1).
GL_SPOT_EXPONENT params is a single integer or floating-point value that
specifies the intensity distribution of the light.
Integer and floating-point values are mapped directly.
Only values in the range [0,128] are accepted.
Effective light intensity is attenuated by the cosine
of the angle between the direction of the light and the
direction from the light to the vertex being lighted,
raised to the power of the spot exponent. Thus, higher
spot exponents result in a more focused light source,
regardless of the spot cutoff angle (see next
paragraph). The default spot exponent is 0, resulting
in uniform light distribution.
GL_SPOT_CUTOFF params is a single integer or floating-point value that
specifies the maximum spread angle of a light source.
Integer and floating-point values are mapped directly.
Only values in the range [0,90], and the special value
180, are accepted. If the angle between the direction
of the light and the direction from the light to the
vertex being lighted is greater than the spot cutoff
angle, the light is completely masked. Otherwise, its
intensity is controlled by the spot exponent and the
attenuation factors. The default spot cutoff is 180,
resulting in uniform light distribution.
GL_CONSTANT_ATTENUATION
GL_LINEAR_ATTENUATION
GL_QUADRATIC_ATTENUATION
params is a single integer or floating-point value that
specifies one of the three light attenuation factors.
Integer and floating-point values are mapped directly.
Only nonnegative values are accepted. If the light is
positional, rather than directional, its intensity is
attenuated by the reciprocal of the sum of: the
constant factor, the linear factor times the distance
between the light and the vertex being lighted, and the
quadratic factor times the square of the same
distance. The default attenuation factors are (1,0,0),
resulting in no attenuation.
Notes
It is always the case that GL_LIGHTi = GL_LIGHT0 + i.
Errors
GL_INVALID_ENUM is generated if either light or pname is not an accepted
value.
GL_INVALID_VALUE is generated if a spot exponent value is specified outside
the range [0,128], or if spot cutoff is specified outside the range [0,90]
(except for the special value 180), or if a negative attenuation factor is
specified.
GL_INVALID_OPERATION is generated if glLight is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetLight
glIsEnabled with argument GL_LIGHTING
See Also
glColorMaterial, glLightModel, glMaterial
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ΓòÉΓòÉΓòÉ 3.65. glLightModel ΓòÉΓòÉΓòÉ
OpenGL man pages
glLightModel
Name
glLightModelf, glLightModeli, glLightModelfv, glLightModeliv - set the
lighting model parameters
C Specification
void glLightModelf( GLenum pname,
GLfloat param )
void glLightModeli( GLenum pname,
GLint param )
Parameters
pname Specifies a single-valued lighting model parameter.
GL_LIGHT_MODEL_LOCAL_VIEWER and GL_LIGHT_MODEL_TWO_SIDE are
accepted.
param Specifies the value that param will be set to.
C Specification
void glLightModelfv( GLenum pname,
const GLfloat *params )
void glLightModeliv( GLenum pname,
const GLint *params )
Parameters
pname
Specifies a lighting model parameter. GL_LIGHT_MODEL_AMBIENT,
GL_LIGHT_MODEL_LOCAL_VIEWER, and GL_LIGHT_MODEL_TWO_SIDE are accepted.
params
Specifies a pointer to the value or values that params will be set to.
Description
glLightModel sets the lighting model parameter. pname names a parameter
and params gives the new value. There are three lighting model parameters:
GL_LIGHT_MODEL_AMBIENT
params contains four integer or floating-point values that
specify the ambient RGBA intensity of the entire scene. Integer
values are mapped linearly such that the most positive
representable value maps to 1.0, and the most negative
representable value maps to -1.0. Floating-point values are
mapped directly. Neither integer nor floating-point values are
clamped. The default ambient scene intensity is (0.2, 0.2, 0.2,
1.0).
GL_LIGHT_MODEL_LOCAL_VIEWER
params is a single integer or floating-point value that specifies
how specular reflection angles are computed. If params is 0 (or
0.0), specular reflection angles take the view direction to be
parallel to and in the direction of the -z axis, regardless of
the location of the vertex in eye coordinates. Otherwise
specular reflections are computed from the origin of the eye
coordinate system. The default is 0.
GL_LIGHT_MODEL_TWO_SIDE
params is a single integer or floating-point value that specifies
whether one- or two-sided lighting calculations are done for
polygons. It has no effect on the lighting calculations for
points, lines, or bitmaps. If params is 0 (or 0.0), one-sided
lighting is specified, and only the front material parameters are
used in the lighting equation. Otherwise, two-sided lighting is
specified. In this case, vertices of back-facing polygons are
lighted using the back material parameters, and have their
normals reversed before the lighting equation is evaluated.
Vertices of front-facing polygons are always lighted using the
front material parameters, with no change to their normals. The
default is 0.
In RGBA mode, the lighted color of a vertex is the sum of the material
emission intensity, the product of the material ambient reflectance and the
lighting model full-scene ambient intensity, and the contribution of each
enabled light source. Each light source contributes the sum of three
terms: ambient, diffuse, and specular. The ambient light source
contribution is the product of the material ambient reflectance and the
light's ambient intensity. The diffuse light source contribution is the
product of the material diffuse reflectance, the light's diffuse intensity,
and the dot product of the vertex's normal with the normalized vector from
the vertex to the light source. The specular light source contribution is
the product of the material specular reflectance, the light's specular
intensity, and the dot product of the normalized vertex-to-eye and vertex-
to-light vectors, raised to the power of the shininess of the material.
All three light source contributions are attenuated equally based on the
distance from the vertex to the light source and on light source direction,
spread exponent, and spread cutoff angle. All dot products are replaced
with zero if they evaluate to a negative value.
The alpha component of the resulting lighted color is set to the alpha
value of the material diffuse reflectance.
In color index mode, the value of the lighted index of a vertex ranges from
the ambient to the specular values passed to glMaterial using
GL_COLOR_INDEXES. Diffuse and specular coefficients, computed with a (.30,
.59, .11) weighting of the lights' colors, the shininess of the material,
and the same reflection and attenuation equations as in the RGBA case,
determine how much above ambient the resulting index is.
Errors
GL_INVALID_ENUM is generated if pname is not an accepted value.
GL_INVALID_OPERATION is generated if glLightModel is called between a call
to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_LIGHT_MODEL_AMBIENT
glGet with argument GL_LIGHT_MODEL_LOCAL_VIEWER
glGet with argument GL_LIGHT_MODEL_TWO_SIDE
glIsEnabled with argument GL_LIGHTING
See Also
glLight, glMaterial
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ΓòÉΓòÉΓòÉ 3.66. glLineStipple ΓòÉΓòÉΓòÉ
OpenGL man pages
glLineStipple
Name
glLineStipple - specify the line stipple pattern
C Specification
void glLineStipple( GLint factor,
GLushort pattern )
Parameters
factor Specifies a multiplier for each bit in the line stipple pattern.
If factor is 3, for example, each bit in the pattern will be used
three times before the next bit in the pattern is used. factor is
clamped to the range [1, 256] and defaults to one.
pattern Specifies a 16-bit integer whose bit pattern determines which
fragments of a line will be drawn when the line is rasterized.
Bit zero is used first, and the default pattern is all ones.
Description
Line stippling masks out certain fragments produced by rasterization; those
fragments will not be drawn. The masking is achieved by using three
parameters: the 16-bit line stipple pattern pattern, the repeat count
factor, and an integer stipple counter s.
Counter s is reset to zero whenever glBegin is called, and before each line
segment of a glBegin(GL_LINES)/glEnd sequence is generated. It is
incremented after each fragment of a unit width aliased line segment is
generated, or after each i fragments of an i width line segment are
generated. The i fragments associated with count s are masked out if
pattern bit (s / factor) mod 16
is zero, otherwise these fragments are sent to the frame buffer. Bit zero
of pattern is the least significant bit.
Antialiased lines are treated as a sequence of 1xwidth rectangles for
purposes of stippling. Rectangle s is rasterized or not based on the
fragment rule described for aliased lines, counting rectangles rather than
groups of fragments.
Line stippling is enabled or disabled using glEnable and glDisable with
argument GL_LINE_STIPPLE. When enabled, the line stipple pattern is
applied as described above. When disabled, it is as if the pattern were
all ones. Initially, line stippling is disabled.
Errors
GL_INVALID_OPERATION is generated if glLineStipple is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_LINE_STIPPLE_PATTERN
glGet with argument GL_LINE_STIPPLE_REPEAT
glIsEnabled with argument GL_LINE_STIPPLE
See Also
glLineWidth, glPolygonStipple
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ΓòÉΓòÉΓòÉ 3.67. glLineWidth ΓòÉΓòÉΓòÉ
OpenGL man pages
glLineWidth
Name
glLineWidth - specify the width of rasterized lines
C Specification
void glLineWidth( GLfloat width )
Parameters
width Specifies the width of rasterized lines. The default is 1.0.
Description
glLineWidth specifies the rasterized width of both aliased and antialiased
lines. Using a line width other than 1.0 has different effects, depending
on whether line antialiasing is enabled. Line antialiasing is controlled
by calling glEnable and glDisable with argument GL_LINE_SMOOTH.
If line antialiasing is disabled, the actual width is determined by
rounding the supplied width to the nearest integer. (If the rounding
results in the value 0, it is as if the line width were 1.) If |dx| >= |dy|,
i pixels are filled in each column that is rasterized, where i is the
rounded value of width. Otherwise, i pixels are filled in each row that is
rasterized.
If antialiasing is enabled, line rasterization produces a fragment for each
pixel square that intersects the region lying within the rectangle having
width equal to the current line width, length equal to the actual length of
the line, and centered on the mathematical line segment. The coverage
value for each fragment is the window coordinate area of the intersection
of the rectangular region with the corresponding pixel square. This value
is saved and used in the final rasterization step.
Not all widths can be supported when line antialiasing is enabled. If an
unsupported width is requested, the nearest supported width is used. Only
width 1.0 is guaranteed to be supported; others depend on the
implementation. The range of supported widths and the size difference
between supported widths within the range can be queried by calling glGet
with arguments GL_LINE_WIDTH_RANGE and GL_LINE_WIDTH_GRANULARITY.
Notes
The line width specified by glLineWidth is always returned when
GL_LINE_WIDTH is queried. Clamping and rounding for aliased and
antialiased lines have no effect on the specified value.
Non-antialiased line width may be clamped to an implementation-dependent
maximum. Although this maximum cannot be queried, it must be no less than
the maximum value for antialiased lines, rounded to the nearest integer
value.
Errors
GL_INVALID_VALUE is generated if width is less than or equal to zero.
GL_INVALID_OPERATION is generated if glLineWidth is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_LINE_WIDTH
glGet with argument GL_LINE_WIDTH_RANGE
glGet with argument GL_LINE_WIDTH_GRANULARITY
glIsEnabled with argument GL_LINE_SMOOTH
See Also
glEnable, glLineSmooth
ΓòÉΓòÉΓòÉ 3.68. glListBase ΓòÉΓòÉΓòÉ
OpenGL man pages
glListBase
Name
glListBase - set the display-list base for glCallLists
C Specification
void glListBase( GLuint base )
Parameters
base Specifies an integer offset that will be added to glCallLists offsets
to generate display-list names. Initial value is zero.
Description
glCallLists specifies an array of offsets. Display-list names are
generated by adding base to each offset. Names that reference valid
display lists are executed; the others are ignored.
Errors
GL_INVALID_OPERATION is generated if glListBase is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_LIST_BASE
See Also
glCallLists
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ΓòÉΓòÉΓòÉ 3.69. glLoadIdentity ΓòÉΓòÉΓòÉ
OpenGL man pages
glLoadIdentity
Name
glLoadIdentity - replace the current matrix with the identity matrix
C Specification
void glLoadIdentity( void )
Description
glLoadIdentity replaces the current matrix with the identity matrix. It is
semantically equivalent to calling glLoadMatrix with the identity matrix
| 1 0 0 0 |
| |
| 0 1 0 0 |
| 0 0 1 0 |
| |
| 0 0 0 1 |
but in some cases it is more efficient.
Errors
GL_INVALID_OPERATION is generated if glLoadIdentity is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glLoadMatrix, glMatrixMode, glMultMatrix, glPushMatrix
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ΓòÉΓòÉΓòÉ 3.70. glLoadMatrix ΓòÉΓòÉΓòÉ
OpenGL man pages
glLoadMatrix
Name
glLoadMatrixd, glLoadMatrixf - replace the current matrix with an arbitrary
matrix
C Specification
void glLoadMatrixd( const GLdouble *m )
void glLoadMatrixf( const GLfloat *m )
Parameters
m Specifies a pointer to a 4x4 matrix stored in column-major order as
sixteen consecutive values.
Description
glLoadMatrix replaces the current matrix with the one specified in m. The
current matrix is the projection matrix, modelview matrix, or texture
matrix, determined by the current matrix mode (see glMatrixMode).
m points to a 4x4 matrix of single- or double-precision floating-point
values stored in column-major order. That is, the matrix is stored as
follows:
|a0 a4 a8 a12|
| |
|a1 a5 a9 a13|
| |
|a2 a6 a10 a14|
| |
|a3 a7 a11 a15|
| |
Errors
GL_INVALID_OPERATION is generated if glLoadMatrix is called between a call
to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glLoadIdentity, glMatrixMode, glMultMatrix, glPushMatrix
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ΓòÉΓòÉΓòÉ 3.71. glLoadName ΓòÉΓòÉΓòÉ
OpenGL man pages
glLoadName
Name
glLoadName - load a name onto the name stack
C Specification
void glLoadName( GLuint name )
Parameters
name Specifies a name that will replace the top value on the name stack.
Description
The name stack is used during selection mode to allow sets of rendering
commands to be uniquely identified. It consists of an ordered set of
unsigned integers. glLoadName causes name to replace the value on the top
of the name stack, which is initially empty.
The name stack is always empty while the render mode is not GL_SELECT.
Calls to glLoadName while the render mode is not GL_SELECT are ignored.
Errors
GL_INVALID_OPERATION is generated if glLoadName is called while the name
stack is empty.
GL_INVALID_OPERATION is generated if glLoadName is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_NAME_STACK_DEPTH
glGet with argument GL_MAX_NAME_STACK_DEPTH
See Also
glInitNames, glPushName, glRenderMode, glSelectBuffer
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ΓòÉΓòÉΓòÉ 3.72. glLogicOp ΓòÉΓòÉΓòÉ
OpenGL man pages
glLogicOp
Name
glLogicOp - specify a logical pixel operation for color index rendering
C Specification
void glLogicOp( GLenum opcode )
Parameters
opcode Specifies a symbolic constant that selects a logical operation.
The following symbols are accepted: GL_CLEAR, GL_SET, GL_COPY,
GL_COPY_INVERTED, GL_NOOP, GL_INVERT, GL_AND, GL_NAND, GL_OR,
GL_NOR, GL_XOR, GL_EQUIV, GL_AND_REVERSE, GL_AND_INVERTED,
GL_OR_REVERSE, and GL_OR_INVERTED.
Description
glLogicOp specifies a logical operation that, when enabled, is applied
between the incoming color index and the color index at the corresponding
location in the frame buffer. The logical operation is enabled or disabled
with glEnable and glDisable using the symbolic constant GL_LOGIC_OP.
opcode is a symbolic constant chosen from the list below. In the
explanation of the logical operations, s represents the incoming color
index and d represents the index in the frame buffer. Standard C-language
operators are used. As these bitwise operators suggest, the logical
operation is applied independently to each bit pair of the source and
destination indices.
------------------------------------
| opcode | resulting value |
------------------------------------
| GL_CLEAR | 0 |
| GL_SET | 1 |
| GL_COPY | s |
|GL_COPY_INVERTED | !s |
| GL_NOOP | d |
| GL_INVERT | !d |
| GL_AND | s & d |
| GL_NAND | !(s & d) |
| GL_OR | s | d |
| GL_NOR | !(s | d) |
| GL_XOR | s ^ d |
| GL_EQUIV | !(s ^ d) |
| GL_AND_REVERSE | s & !d |
|GL_AND_INVERTED | !s & d |
| GL_OR_REVERSE | s | !d |
| GL_OR_INVERTED | !s | d |
------------------------------------
Notes
Logical pixel operations are not applied to RGBA color buffers.
When more than one color index buffer is enabled for drawing, logical
operations are done separately for each enabled buffer, using for the
destination index the contents of that buffer (see glDrawBuffer).
opcode must be one of the sixteen accepted values. Other values result in
an error.
Errors
GL_INVALID_ENUM is generated if opcode is not an accepted value.
GL_INVALID_OPERATION is generated if glLogicOp is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_LOGIC_OP_MODE
glIsEnabled with argument GL_LOGIC_OP
See Also
glAlphaFunc, glBlendFunc, glDrawBuffer, glEnable, glStencilOp
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ΓòÉΓòÉΓòÉ 3.73. glMap1 ΓòÉΓòÉΓòÉ
OpenGL man pages
glMap1
Name
glMap1d, glMap1f - define a one-dimensional evaluator
C Specification
void glMap1d( GLenum target,
GLdouble u1,
GLdouble u2,
GLint stride,
GLint order,
const GLdouble *points )
void glMap1f( GLenum target,
GLfloat u1,
GLfloat u2,
GLint stride,
GLint order,
const GLfloat *points )
Parameters
target Specifies the kind of values that are generated by the evaluator.
Symbolic constants GL_MAP1_VERTEX_3, GL_MAP1_VERTEX_4,
GL_MAP1_INDEX, GL_MAP1_COLOR_4, GL_MAP1_NORMAL,
GL_MAP1_TEXTURE_COORD_1, GL_MAP1_TEXTURE_COORD_2,
GL_MAP1_TEXTURE_COORD_3, and GL_MAP1_TEXTURE_COORD_4 are accepted.
u1, u2 Specify a linear mapping of u, as presented to glEvalCoord1, to u,
the variable that is evaluated by the equations specified by this
command.
stride Specifies the number of floats or doubles between the beginning of
one control point and the beginning of the next one in the data
structure referenced in points. This allows control points to be
embedded in arbitrary data structures. The only constraint is that
the values for a particular control point must occupy contiguous
memory locations.
order Specifies the number of control points. Must be positive.
points Specifies a pointer to the array of control points.
Description
Evaluators provide a way to use polynomial or rational polynomial mapping
to produce vertices, normals, texture coordinates, and colors. The values
produced by an evaluator are sent to further stages of GL processing just
as if they had been presented using glVertex, glNormal, glTexCoord, and
glColor commands, except that the generated values do not update the
current normal, texture coordinates, or color.
All polynomial or rational polynomial splines of any degree (up to the
maximum degree supported by the GL implementation) can be described using
evaluators. These include almost all splines used in computer graphics,
including B-splines, Bezier curves, Hermite splines, and so on.
Evaluators define curves based on Bernstein polynomials. Define p(u) as
n
---
\ n
p(u) = \ B (u)R
/ i i
/
---
i=0
n
where R is a control point and B (u) is the ith Bernstein polynomial of
i i
degree n (order = n+1):
n |n| i n-i
B (u) = | | u (1-u)
i |i|
Recall that
0 |n|
0 = 1 and | | = 1
|0|
glMap1 is used to define the basis and to specify what kind of values are
produced. Once defined, a map can be enabled and disabled by calling
glEnable and glDisable with the map name, one of the nine predefined values
for target described below. glEvalCoord1 evaluates the one-dimensional
maps that are enabled. When glEvalCoord1 presents a value u, the Bernstein
functions are evaluated using u, where
u - u1
u = -------
u2 - u1
target is a symbolic constant that indicates what kind of control points
are provided in points, and what output is generated when the map is
evaluated. It can assume one of nine predefined values:
GL_MAP1_VERTEX_3 Each control point is three floating-point values
representing x, y, and z. Internal glVertex3
commands are generated when the map is evaluated.
GL_MAP1_VERTEX_4 Each control point is four floating-point values
representing x, y, z, and w. Internal glVertex4
commands are generated when the map is evaluated.
GL_MAP1_INDEX Each control point is a single floating-point
value representing a color index. Internal
glIndex commands are generated when the map is
evaluated. The current index is not updated with
the value of these glIndex commands, however.
GL_MAP1_COLOR_4 Each control point is four floating-point values
representing red, green, blue, and alpha.
Internal glColor4 commands are generated when the
map is evaluated. The current color is not
updated with the value of these glColor4 commands,
however.
GL_MAP1_NORMAL Each control point is three floating-point values
representing the x, y, and z components of a
normal vector. Internal glNormal commands are
generated when the map is evaluated. The current
normal is not updated with the value of these
glNormal commands, however.
GL_MAP1_TEXTURE_COORD_1 Each control point is a single floating-point
value representing the s texture coordinate.
Internal glTexCoord1 commands are generated when
the map is evaluated. The current texture
coordinates are not updated with the value of
these glTexCoord commands, however.
GL_MAP1_TEXTURE_COORD_2 Each control point is two floating-point values
representing the s and t texture coordinates.
Internal glTexCoord2 commands are generated when
the map is evaluated. The current texture
coordinates are not updated with the value of
these glTexCoord commands, however.
GL_MAP1_TEXTURE_COORD_3 Each control point is three floating-point values
representing the s, t, and r texture coordinates.
Internal glTexCoord3 commands are generated when
the map is evaluated. The current texture
coordinates are not updated with the value of
these glTexCoord commands, however.
GL_MAP1_TEXTURE_COORD_4 Each control point is four floating-point values
representing the s, t, r, and q texture
coordinates. Internal glTexCoord4 commands are
generated when the map is evaluated. The current
texture coordinates are not updated with the value
of these glTexCoord commands, however.
stride, order, and points define the array addressing for accessing the
control points. points is the location of the first control point, which
occupies one, two, three, or four contiguous memory locations, depending on
which map is being defined. order is the number of control points in the
array. stride tells how many float or double locations to advance the
internal memory pointer to reach the next control point.
Notes
As is the case with all GL commands that accept pointers to data, it is as
if the contents of points were copied by glMap1 before it returned.
Changes to the contents of points have no effect after glMap1 is called.
Errors
GL_INVALID_ENUM is generated if target is not an accepted value.
GL_INVALID_VALUE is generated if u1 is equal to u2.
GL_INVALID_VALUE is generated if stride is less than the number of values
in a control point.
GL_INVALID_VALUE is generated if order is less than one or greater than
GL_MAX_EVAL_ORDER.
GL_INVALID_OPERATION is generated if glMap1 is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetMap
glGet with argument GL_MAX_EVAL_ORDER
glIsEnabled with argument GL_MAP1_VERTEX_3
glIsEnabled with argument GL_MAP1_VERTEX_4
glIsEnabled with argument GL_MAP1_INDEX
glIsEnabled with argument GL_MAP1_COLOR_4
glIsEnabled with argument GL_MAP1_NORMAL
glIsEnabled with argument GL_MAP1_TEXTURE_COORD_1
glIsEnabled with argument GL_MAP1_TEXTURE_COORD_2
glIsEnabled with argument GL_MAP1_TEXTURE_COORD_3
glIsEnabled with argument GL_MAP1_TEXTURE_COORD_4
See Also
glBegin, glColor, glEnable, glEvalCoord, glEvalMesh, glEvalPoint, glMap2,
glMapGrid, glNormal, glTexCoord, glVertex
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Introduction | Alphabetic | Specification
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ΓòÉΓòÉΓòÉ 3.74. glMap2 ΓòÉΓòÉΓòÉ
OpenGL man pages
glMap2
Name
glMap2d, glMap2f - define a two-dimensional evaluator
C Specification
void glMap2d( GLenum target,
GLdouble u1,
GLdouble u2,
GLint ustride,
GLint uorder,
GLdouble v1,
GLdouble v2,
GLint vstride,
GLint vorder,
const GLdouble *points )
void glMap2f( GLenum target,
GLfloat u1,
GLfloat u2,
GLint ustride,
GLint uorder,
GLfloat v1,
GLfloat v2,
GLint vstride,
GLint vorder,
const GLfloat *points )
Parameters
target Specifies the kind of values that are generated by the evaluator.
Symbolic constants GL_MAP2_VERTEX_3, GL_MAP2_VERTEX_4,
GL_MAP2_INDEX, GL_MAP2_COLOR_4, GL_MAP2_NORMAL,
GL_MAP2_TEXTURE_COORD_1, GL_MAP2_TEXTURE_COORD_2,
GL_MAP2_TEXTURE_COORD_3, and GL_MAP2_TEXTURE_COORD_4 are accepted.
u1, u2 Specify a linear mapping of u, as presented to glEvalCoord2, to u,
one of the two variables that is evaluated by the equations
specified by this command.
ustride Specifies the number of floats or doubles between the beginning of
control point R and the beginning of control point R ,
ij (i+1) j
where i and j are the u and v control point indices, respectively.
This allows control points to be embedded in arbitrary data
structures. The only constraint is that the values for a
particular control point must occupy contiguous memory locations.
uorder Specifies the dimension of the control point array in the u axis.
Must be positive.
v1, v2 Specify a linear mapping of v, as presented to glEvalCoord2, to v,
one of the two variables that is evaluated by the equations
specified by this command.
vstride Specifies the number of floats or doubles between the beginning of
control point R and the beginning of control point R ,
ij (i+1) j
where i and j are the u and v control point indices, respectively.
This allows control points to be embedded in arbitrary data
structures. The only constraint is that the values for a
particular control point must occupy contiguous memory locations.
vorder Specifies the dimension of the control point array in the v axis.
Must be positive.
points Specifies a pointer to the array of control points.
Description
Evaluators provide a way to use polynomial or rational polynomial mapping
to produce vertices, normals, texture coordinates, and colors. The values
produced by an evaluator are sent on to further stages of GL processing
just as if they had been presented using glVertex, glNormal, glTexCoord,
and glColor commands, except that the generated values do not update the
current normal, texture coordinates, or color.
All polynomial or rational polynomial splines of any degree (up to the
maximum degree supported by the GL implementation) can be described using
evaluators. These include almost all surfaces used in computer graphics,
including B-spline surfaces, NURBS surfaces, Bezier surfaces, and so on.
Evaluators define surfaces based on bivariate Bernstein polynomials.
Define p(u,v) as
n m
--- ---
\ \ n m
p(u,v) = \ \ B (u)B (v) R
/ / i j ij
/ /
--- ---
i=0 j=0
n
where R is a control point, B (u) is the ith Bernstein polynomial of
ij i
degree n (uorder = n+1)
n |n| i n-i
B (u) = | |u (1-u)
i |i|
m
and B (v') is the jth Bernstein polynomial of degree m (vorder = m+1)
j
m |m| j m-j
B (v) = | |v (1-v)
j |j|
Recall that
0 |n|
0 = 1 and | | = 1
|0|
glMap2 is used to define the basis and to specify what kind of values are
produced. Once defined, a map can be enabled and disabled by calling
glEnable and glDisable with the map name, one of the nine predefined values
for target, described below. When glEvalCoord2 presents values u and v,
the bivariate Bernstein polynomials are evaluated using u and v, where
u - u1
u = -------
u2 - u1
v - v1
v = -------
v2 - v1
target is a symbolic constant that indicates what kind of control points
are provided in points, and what output is generated when the map is
evaluated. It can assume one of nine predefined values:
GL_MAP2_VERTEX_3 Each control point is three floating-point values
representing x, y, and z. Internal glVertex3
commands are generated when the map is evaluated.
GL_MAP2_VERTEX_4 Each control point is four floating-point values
representing x, y, z, and w. Internal glVertex4
commands are generated when the map is evaluated.
GL_MAP2_INDEX Each control point is a single floating-point
value representing a color index. Internal
glIndex commands are generated when the map is
evaluated. The current index is not updated with
the value of these glIndex commands, however.
GL_MAP2_COLOR_4 Each control point is four floating-point values
representing red, green, blue, and alpha.
Internal glColor4 commands are generated when the
map is evaluated. The current color is not
updated with the value of these glColor4 commands,
however.
GL_MAP2_NORMAL Each control point is three floating-point values
representing the x, y, and z components of a
normal vector. Internal glNormal commands are
generated when the map is evaluated. The current
normal is not updated with the value of these
glNormal commands, however.
GL_MAP2_TEXTURE_COORD_1 Each control point is a single floating-point
value representing the s texture coordinate.
Internal glTexCoord1 commands are generated when
the map is evaluated. The current texture
coordinates are not updated with the value of
these glTexCoord commands, however.
GL_MAP2_TEXTURE_COORD_2 Each control point is two floating-point values
representing the s and t texture coordinates.
Internal glTexCoord2 commands are generated when
the map is evaluated. The current texture
coordinates are not updated with the value of
these glTexCoord commands, however.
GL_MAP2_TEXTURE_COORD_3 Each control point is three floating-point values
representing the s, t, and r texture coordinates.
Internal glTexCoord3 commands are generated when
the map is evaluated. The current texture
coordinates are not updated with the value of
these glTexCoord commands, however.
GL_MAP2_TEXTURE_COORD_4 Each control point is four floating-point values
representing the s, t, r, and q texture
coordinates. Internal glTexCoord4 commands are
generated when the map is evaluated. The current
texture coordinates are not updated with the value
of these glTexCoord commands, however.
ustride, uorder, vstride, vorder, and points define the array addressing
for accessing the control points. points is the location of the first
control point, which occupies one, two, three, or four contiguous memory
locations, depending on which map is being defined. There are
uorderxvorder control points in the array. ustride tells how many float or
double locations are skipped to advance the internal memory pointer from
control point R to control point R . vstride tells how many float
ij (i+1)j
or double locations are skipped to advance the internal memory pointer from
control point R to control point R .
ij i(j+1)
Notes
As is the case with all GL commands that accept pointers to data, it is as
if the contents of points were copied by glMap2 before it returned.
Changes to the contents of points have no effect after glMap2 is called.
Errors
GL_INVALID_ENUM is generated if target is not an accepted value.
GL_INVALID_VALUE is generated if u1 is equal to u2, or if v1 is equal to
v2.
GL_INVALID_VALUE is generated if either ustride or vstride is less than the
number of values in a control point.
GL_INVALID_VALUE is generated if either uorder or vorder is less than one
or greater than GL_MAX_EVAL_ORDER.
GL_INVALID_OPERATION is generated if glMap2 is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetMap
glGet with argument GL_MAX_EVAL_ORDER
glIsEnabled with argument GL_MAP2_VERTEX_3
glIsEnabled with argument GL_MAP2_VERTEX_4
glIsEnabled with argument GL_MAP2_INDEX
glIsEnabled with argument GL_MAP2_COLOR_4
glIsEnabled with argument GL_MAP2_NORMAL
glIsEnabled with argument GL_MAP2_TEXTURE_COORD_1
glIsEnabled with argument GL_MAP2_TEXTURE_COORD_2
glIsEnabled with argument GL_MAP2_TEXTURE_COORD_3
glIsEnabled with argument GL_MAP2_TEXTURE_COORD_4
See Also
glBegin, glColor, glEnable, glEvalCoord, glEvalMesh, glEvalPoint, glMap1,
glMapGrid, glNormal, glTexCoord, glVertex
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.75. glMapGrid ΓòÉΓòÉΓòÉ
OpenGL man pages
glMapGrid
Name
glMapGrid1d, glMapGrid1f, glMapGrid2d, glMapGrid2f - define a one- or two-
dimensional mesh
C Specification
void glMapGrid1d( GLint un,
GLdouble u1,
GLdouble u2 )
void glMapGrid1f( GLint un,
GLfloat u1,
GLfloat u2 )
void glMapGrid2d( GLint un,
GLdouble u1,
GLdouble u2,
GLint vn,
GLdouble v1,
GLdouble v2 )
void glMapGrid2f( GLint un,
GLfloat u1,
GLfloat u2,
GLint vn,
GLfloat v1,
GLfloat v2 )
Parameters
un Specifies the number of partitions in the grid range interval [u1, u2].
Must be positive.
u1, u2
Specify the mappings for integer grid domain values i=0 and i=un.
vn Specifies the number of partitions in the grid range interval [v1, v2]
(glMapGrid2 only).
v1, v2
Specify the mappings for integer grid domain values j=0 and j=vn
(glMapGrid2 only).
Description
glMapGrid and glEvalMesh are used in tandem to efficiently generate and
evaluate a series of evenly spaced map domain values. glEvalMesh steps
through the integer domain of a one- or two-dimensional grid, whose range
is the domain of the evaluation maps specified by glMap1 and glMap2.
glMapGrid1 and glMapGrid2 specify the linear grid mappings between the i
(or i and j) integer grid coordinates, to the u (or u and v) floating-point
evaluation map coordinates. See glMap1 and glMap2 for details of how u and
v coordinates are evaluated.
glMapGrid1 specifies a single linear mapping such that integer grid
coordinate 0 maps exactly to u1, and integer grid coordinate un maps
exactly to u2. All other integer grid coordinates i are mapped such that
u = i(u2-u1)/un + u1
glMapGrid2 specifies two such linear mappings. One maps integer grid
coordinate i=0 exactly to u1, and integer grid coordinate i=un exactly to
u2. The other maps integer grid coordinate j=0 exactly to v1, and integer
grid coordinate j=vn exactly to v2. Other integer grid coordinates i and j
are mapped such that
u = i(u2-u1)/un + u1
v = j(v2-v1)/vn + v1
The mappings specified by glMapGrid are used identically by glEvalMesh and
glEvalPoint.
Errors
GL_INVALID_VALUE is generated if either un or vn is not positive.
GL_INVALID_OPERATION is generated if glMapGrid is called between a call to
glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_MAP1_GRID_DOMAIN
glGet with argument GL_MAP2_GRID_DOMAIN
glGet with argument GL_MAP1_GRID_SEGMENTS
glGet with argument GL_MAP2_GRID_SEGMENTS
See Also
glEvalCoord, glEvalMesh, glEvalPoint, glMap1, glMap2
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Introduction | Alphabetic | Specification
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ΓòÉΓòÉΓòÉ 3.76. glMaterial ΓòÉΓòÉΓòÉ
OpenGL man pages
glMaterial
Name
glMaterialf, glMateriali, glMaterialfv, glMaterialiv - specify material
parameters for the lighting model
C Specification
void glMaterialf( GLenum face,
GLenum pname,
GLfloat param )
void glMateriali( GLenum face,
GLenum pname,
GLint param )
Parameters
face Specifies which face or faces are being updated. Must be one of
GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK.
pname Specifies the single-valued material parameter of the face or faces
that is being updated. Must be GL_SHININESS.
param Specifies the value that parameter GL_SHININESS will be set to.
C Specification
void glMaterialfv( GLenum face,
GLenum pname,
const GLfloat *params )
void glMaterialiv( GLenum face,
GLenum pname,
const GLint *params )
Parameters
face Specifies which face or faces are being updated. Must be one of
GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK.
pname
Specifies the material parameter of the face or faces that is being
updated. Must be one of GL_AMBIENT, GL_DIFFUSE, GL_SPECULAR,
GL_EMISSION, GL_SHININESS, GL_AMBIENT_AND_DIFFUSE, or
GL_COLOR_INDEXES.
params
Specifies a pointer to the value or values that pname will be set to.
Description
glMaterial assigns values to material parameters. There are two matched
sets of material parameters. One, the front-facing set, is used to shade
points, lines, bitmaps, and all polygons (when two-sided lighting is
disabled), or just front-facing polygons (when two-sided lighting is
enabled). The other set, back-facing, is used to shade back-facing
polygons only when two-sided lighting is enabled. Refer to the
glLightModel reference page for details concerning one- and two-sided
lighting calculations.
glMaterial takes three arguments. The first, face, specifies whether the
GL_FRONT materials, the GL_BACK materials, or both GL_FRONT_AND_BACK
materials will be modified. The second, pname, specifies which of several
parameters in one or both sets will be modified. The third, params,
specifies what value or values will be assigned to the specified parameter.
Material parameters are used in the lighting equation that is optionally
applied to each vertex. The equation is discussed in the glLightModel
reference page. The parameters that can be specified using glMaterial, and
their interpretations by the lighting equation, are as follows:
GL_AMBIENT params contains four integer or floating-point values
that specify the ambient RGBA reflectance of the
material. Integer values are mapped linearly such that
the most positive representable value maps to 1.0, and
the most negative representable value maps to -1.0.
Floating-point values are mapped directly. Neither
integer nor floating-point values are clamped. The
default ambient reflectance for both front- and back-
facing materials is (0.2, 0.2, 0.2, 1.0).
GL_DIFFUSE params contains four integer or floating-point values
that specify the diffuse RGBA reflectance of the
material. Integer values are mapped linearly such that
the most positive representable value maps to 1.0, and
the most negative representable value maps to -1.0.
Floating-point values are mapped directly. Neither
integer nor floating-point values are clamped. The
default diffuse reflectance for both front- and back-
facing materials is (0.8, 0.8, 0.8, 1.0).
GL_SPECULAR params contains four integer or floating-point values
that specify the specular RGBA reflectance of the
material. Integer values are mapped linearly such that
the most positive representable value maps to 1.0, and
the most negative representable value maps to -1.0.
Floating-point values are mapped directly. Neither
integer nor floating-point values are clamped. The
default specular reflectance for both front- and back-
facing materials is (0.0, 0.0, 0.0, 1.0).
GL_EMISSION params contains four integer or floating-point values
that specify the RGBA emitted light intensity of the
material. Integer values are mapped linearly such that
the most positive representable value maps to 1.0, and
the most negative representable value maps to -1.0.
Floating-point values are mapped directly. Neither
integer nor floating-point values are clamped. The
default emission intensity for both front- and back-
facing materials is (0.0, 0.0, 0.0, 1.0).
GL_SHININESS params is a single integer or floating-point value that
specifies the RGBA specular exponent of the material.
Integer and floating-point values are mapped directly.
Only values in the range [0,128] are accepted. The
default specular exponent for both front- and back-
facing materials is 0.
GL_AMBIENT_AND_DIFFUSE
Equivalent to calling glMaterial twice with the same
parameter values, once with GL_AMBIENT and once with
GL_DIFFUSE.
GL_COLOR_INDEXES params contains three integer or floating-point values
specifying the color indices for ambient, diffuse, and
specular lighting. These three values, and
GL_SHININESS, are the only material values used by the
color index mode lighting equation. Refer to the
glLightModel reference page for a discussion of color
index lighting.
Notes
The material parameters can be updated at any time. In particular,
glMaterial can be called between a call to glBegin and the corresponding
call to glEnd. If only a single material parameter is to be changed per
vertex, however, glColorMaterial is preferred over glMaterial (see
glColorMaterial).
Errors
GL_INVALID_ENUM is generated if either face or pname is not an accepted
value.
GL_INVALID_VALUE is generated if a specular exponent outside the range
[0,128] is specified.
Associated Gets
glGetMaterial
See Also
glColorMaterial, glLight, glLightModel
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.77. glMatrixMode ΓòÉΓòÉΓòÉ
OpenGL man pages
glMatrixMode
Name
glMatrixMode - specify which matrix is the current matrix
C Specification
void glMatrixMode( GLenum mode )
Parameters
mode Specifies which matrix stack is the target for subsequent matrix
operations. Three values are accepted: GL_MODELVIEW, GL_PROJECTION,
and GL_TEXTURE. The default value is GL_MODELVIEW.
Description
glMatrixMode sets the current matrix mode. mode can assume one of three
values:
GL_MODELVIEW Applies subsequent matrix operations to the modelview
matrix stack.
GL_PROJECTION Applies subsequent matrix operations to the projection
matrix stack.
GL_TEXTURE Applies subsequent matrix operations to the texture
matrix stack.
Errors
GL_INVALID_ENUM is generated if mode is not an accepted value.
GL_INVALID_OPERATION is generated if glMatrixMode is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
See Also
glLoadMatrix, glPushMatrix
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ΓòÉΓòÉΓòÉ 3.78. glMultMatrix ΓòÉΓòÉΓòÉ
OpenGL man pages
glMultMatrix
Name
glMultMatrixd, glMultMatrixf - multiply the current matrix by an arbitrary
matrix
C Specification
void glMultMatrixd( const GLdouble *m )
void glMultMatrixf( const GLfloat *m )
Parameters
m Specifies a pointer a to 4x4 matrix stored in column-major order as
sixteen consecutive values.
Description
glMultMatrix multiplies the current matrix with the one specified in m.
That is, if M is the current matrix and T is the matrix passed to
glMultMatrix, then M is replaced with M Γòû T.
The current matrix is the projection matrix, modelview matrix, or texture
matrix, determined by the current matrix mode (see glMatrixMode).
m points to a 4x4 matrix of single- or double-precision floating-point
values stored in column-major order. That is, the matrix is stored as
|a0 a4 a8 a12|
| |
|a1 a5 a9 a13|
| |
|a2 a6 a10 a14|
| |
|a3 a7 a11 a15|
Errors
GL_INVALID_OPERATION is generated if glMultMatrix is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glMatrixMode, glLoadIdentity, glLoadMatrix, glPushMatrix
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ΓòÉΓòÉΓòÉ 3.79. glNewList ΓòÉΓòÉΓòÉ
OpenGL man pages
glNewList
Name
glNewList, glEndList - create or replace a display list
C Specification
void glNewList( GLuint list,
GLenum mode )
Parameters
list Specifies the display list name.
mode Specifies the compilation mode, which can be GL_COMPILE or
GL_COMPILE_AND_EXECUTE.
C Specification
void glEndList( void )
Description
Display lists are groups of GL commands that have been stored for
subsequent execution. The display lists are created with glNewList. All
subsequent commands are placed in the display list, in the order issued,
until glEndList is called.
glNewList has two arguments. The first argument, list, is a positive
integer that becomes the unique name for the display list. Names can be
created and reserved with glGenLists and tested for uniqueness with
glIsList. The second argument, mode, is a symbolic constant that can
assume one of two values:
GL_COMPILE Commands are merely compiled.
GL_COMPILE_AND_EXECUTE
Commands are executed as they are compiled into the
display list.
Certain commands are not compiled into the display list, but are executed
immediately, regardless of the display-list mode. These commands are
glIsList, glGenLists, glDeleteLists, glFeedbackBuffer, glSelectBuffer,
glRenderMode, glReadPixels, glPixelStore, glFlush, glFinish,
glIsEnabled,
and all of the glGet routines.
When glEndList is encountered, the display-list definition is completed by
associating the list with the unique name list (specified in the glNewList
command). If a display list with name list already exists, it is replaced
only when glEndList is called.
Notes
glCallList and glCallLists can be entered into display lists. The commands
in the display list or lists executed by glCallList or glCallLists are not
included in the display list being created, even if the list creation mode
is GL_COMPILE_AND_EXECUTE.
A display list is just a group of commands and arguments, so errors
generated by commands in a display list must be generated when the list is
executed. If the list is created in GL_COMPILE mode, errors are not
generated until the list is executed.
Errors
GL_INVALID_VALUE is generated if list is zero.
GL_INVALID_ENUM is generated if mode is not an accepted value.
GL_INVALID_OPERATION is generated if glEndList is called without a
preceding glNewList, or if glNewList is called while a display list is
being defined.
GL_INVALID_OPERATION is generated if glNewList or glEndList is executed
between the execution of glBegin and the corresponding execution of glEnd.
GL_OUT_OF_MEMORY is generated if there is insufficient memory to compile
the display list.
Associated Gets
glIsList
See Also
glCallList, glCallLists, glDeleteLists, glGenLists
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ΓòÉΓòÉΓòÉ 3.80. glNormal ΓòÉΓòÉΓòÉ
OpenGL man pages
glNormal
Name
glNormal3b, glNormal3d, glNormal3f, glNormal3i, glNormal3s,
glNormal3bv,
glNormal3dv, glNormal3fv, glNormal3iv, glNormal3sv - set the current normal
vector
C Specification
void glNormal3b( GLbyte nx,
GLbyte ny,
GLbyte nz )
void glNormal3d( GLdouble nx,
GLdouble ny,
GLdouble nz )
void glNormal3f( GLfloat nx,
GLfloat ny,
GLfloat nz )
void glNormal3i( GLint nx,
GLint ny,
GLint nz )
void glNormal3s( GLshort nx,
GLshort ny,
GLshort nz )
Parameters
nx, ny, nz
Specify the x, y, and z coordinates of the new current normal.
The initial value of the current normal is (0,0,1).
C Specification
void glNormal3bv( const GLbyte *v )
void glNormal3dv( const GLdouble *v )
void glNormal3fv( const GLfloat *v )
void glNormal3iv( const GLint *v )
void glNormal3sv( const GLshort *v )
Parameters
v Specifies a pointer to an array of three elements: the x, y, and z
coordinates of the new current normal.
Description
The current normal is set to the given coordinates whenever glNormal is
issued. Byte, short, or integer arguments are converted to floating-point
format with a linear mapping that maps the most positive representable
integer value to 1.0, and the most negative representable integer value to
-1.0.
Normals specified with glNormal need not have unit length. If
normalization is enabled, then normals specified with glNormal are
normalized after transformation. Normalization is controlled using
glEnable and glDisable with the argument GL_NORMALIZE. By default,
normalization is disabled.
Notes
The current normal can be updated at any time. In particular, glNormal can
be called between a call to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_CURRENT_NORMAL
glIsEnable with argument GL_NORMALIZE
See Also
glBegin, glColor, glIndex, glTexCoord, glVertex
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ΓòÉΓòÉΓòÉ 3.81. glNormalPointerEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glNormalPointerEXT
Name
glNormalPointerEXT - define a array of normals
C Specification
void glNormalPointerEXT( GLenum type,
GLsizei stride,
GLsizei count,
const GLvoid *pointer )
Parameters
type Specifies the the data type of each coordinate in the array.
Symbolic constants GL_BYTE, GL_SHORT, GL_INT, GL_FLOAT, or
GL_DOUBLE_EXT are accepted.
stride Specifies the byte offset between consecutive normals.
count Specifies the number of normals, counting from the first, that are
static.
pointer Specifies a pointer to the first coordinate of the first normal in
the array.
Description
glNormalPointerEXT specifies the location and data format of an array of
normals to use when rendering using the vertex array extension. type specifies
the data type of the normal coordinates and stride gives the byte stride
from one normal to the next allowing vertexes and attributes to be packed
into a single array or stored in separate arrays. (Single-array storage may
be more efficient on some implementations.) count indicates the number of
array elements (counting from the first) that are static. Static elements
may be modified by the application, but once they are modified, the
application must explicitly respecify the array before using it for any
rendering. When a normal array is specified, type, stride, count and pointer
are saved as client-side state, and static array elements may be cached by
the implementation.
The normal array is enabled and disabled using glEnable and glDisable with
the argument GL_NORMAL_ARRAY_EXT. If enabled, the normal array is used when
glDrawArraysEXT or glArrayElementEXT is called.
Use glDrawArraysEXT to define a sequence of primitives (all of the same
type) from pre-specified vertex and vertex attribute arrays. Use
glArrayElementEXT to specify primitives by indexing vertexes and vertex
attributes.
Notes
Non-static array elements are not accessed until glArrayElementEXT or
glDrawArraysEXT is executed.
By default the normal array is disabled and it won't be accessed when
glArrayElementEXT or glDrawArraysEXT is called.
Although it is not an error to call glNormalPointerEXT between the
execution of glBegin and the corresponding execution of glEnd, the results
are undefined.
glNormalPointerEXT will typically be implemented on the client side with no
protocol.
Since the normal array parameters are client side state, they are not saved
or restored by glPushAttrib and glPopAttrib.
glNormalPointerEXT commands are not entered into display lists.
glNormalPointerEXT is part of the EXT_vertex_array extension, not
part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
Errors
GL_INVALID_ENUM is generated if type is not an accepted value.
GL_INVALID_VALUE is generated if stride or count is negative.
Associated Gets
glIsEnabled with argument GL_NORMAL_ARRAY_EXT
glGet with argument GL_NORMAL_ARRAY_TYPE_EXT
glGet with argument GL_NORMAL_ARRAY_STRIDE_EXT
glGet with argument GL_NORMAL_ARRAY_COUNT_EXT
glGetPointervEXT with argument GL_NORMAL_ARRAY_POINTER_EXT
See Also
glArrayElementEXT, glColorPointerEXT, glDrawArraysEXT,
glEdgeFlagPointerEXT, glGetPointervEXT, glIndexPointerEXT,
glTexCoordPointerEXT, glVertexPointerEXT, glEnable
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ΓòÉΓòÉΓòÉ 3.82. glOrtho ΓòÉΓòÉΓòÉ
OpenGL man pages
glOrtho
Name
glOrtho - multiply the current matrix by an orthographic matrix
C Specification
void glOrtho( GLdouble left,
GLdouble right,
GLdouble bottom,
GLdouble top,
GLdouble near,
GLdouble far )
Parameters
left, right Specify the coordinates for the left and right vertical
clipping planes.
bottom, top Specify the coordinates for the bottom and top horizontal
clipping planes.
near, far Specify the distances to the nearer and farther depth clipping
planes. These distances are negative if the plane is to be
behind the viewer.
Description
glOrtho describes a perspective matrix that produces a parallel projection.
(left, bottom, -near) and (right, top, -near) specify the points on the
near clipping plane that are mapped to the lower left and upper right
corners of the window, respectively, assuming that the eye is located at
(0, 0, 0). -far specifies the location of the far clipping plane. Both
near and far can be either positive or negative. The corresponding matrix
is
| 2 |
|---------- 0 0 t |
|right-left x |
| |
| 2 |
| 0 ---------- 0 t |
| top-bottom y |
| |
| |
| 0 0 -2 |
| -------- t |
| far-near z |
| |
| 0 0 0 1 |
where
right+left
t = - ----------
x right-left
top+bottom
t = - ----------
y top-bottom
far+near
t = - --------
z far-near
The current matrix is multiplied by this matrix with the result replacing
the current matrix. That is, if M is the current matrix and O is the ortho
matrix, then M is replaced with M Γòû O.
Use glPushMatrix and glPopMatrix to save and restore the current matrix
stack.
Errors
GL_INVALID_OPERATION is generated if glOrtho is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glFrustum, glMatrixMode, glMultMatrix, glPushMatrix, glViewport
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ΓòÉΓòÉΓòÉ 3.83. glPassThrough ΓòÉΓòÉΓòÉ
OpenGL man pages
glPassThrough
Name
glPassThrough - place a marker in the feedback buffer
C Specification
void glPassThrough( GLfloat token )
Parameters
token Specifies a marker value to be placed in the feedback buffer
following a GL_PASS_THROUGH_TOKEN.
Description
Feedback is a GL render mode. The mode is selected by calling glRenderMode
with GL_FEEDBACK. When the GL is in feedback mode, no pixels are produced
by rasterization. Instead, information about primitives that would have
been rasterized is fed back to the application using the GL. See
glFeedbackBuffer for a description of the feedback buffer and the values in
it.
glPassThrough inserts a user-defined marker in the feedback buffer when it
is executed in feedback mode. token is returned as if it were a primitive;
it is indicated with its own unique identifying value:
GL_PASS_THROUGH_TOKEN. The order of glPassThrough commands with respect to
the specification of graphics primitives is maintained.
Notes
glPassThrough is ignored if the GL is not in feedback mode.
Errors
GL_INVALID_OPERATION is generated if glPassThrough is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_RENDER_MODE
See Also
glFeedbackBuffer, glRenderMode
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ΓòÉΓòÉΓòÉ 3.84. glPixelMap ΓòÉΓòÉΓòÉ
OpenGL man pages
glPixelMap
Name
glPixelMapfv, glPixelMapuiv, glPixelMapusv - set up pixel transfer maps
C Specification
void glPixelMapfv( GLenum map,
GLint mapsize,
const GLfloat *values )
void glPixelMapuiv( GLenum map,
GLint mapsize,
const GLuint *values )
void glPixelMapusv( GLenum map,
GLint mapsize,
const GLushort *values )
Parameters
map Specifies a symbolic map name. Must be one of the following:
GL_PIXEL_MAP_I_TO_I, GL_PIXEL_MAP_S_TO_S, GL_PIXEL_MAP_I_TO_R,
GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B, GL_PIXEL_MAP_I_TO_A,
GL_PIXEL_MAP_R_TO_R, GL_PIXEL_MAP_G_TO_G, GL_PIXEL_MAP_B_TO_B, or
GL_PIXEL_MAP_A_TO_A.
mapsize Specifies the size of the map being defined.
values Specifies an array of mapsize values.
Description
glPixelMap sets up translation tables, or maps, used by glDrawPixels,
glReadPixels, glCopyPixels, glTexImage1D, and glTexImage2D. Use of these
maps is described completely in the glPixelTransfer reference page, and
partly in the reference pages for the pixel and texture image commands.
Only the specification of the maps is described in this reference page.
map is a symbolic map name, indicating one of ten maps to set. mapsize
specifies the number of entries in the map, and values is a pointer to an
array of mapsize map values.
The ten maps are as follows:
GL_PIXEL_MAP_I_TO_I Maps color indices to color indices.
GL_PIXEL_MAP_S_TO_S Maps stencil indices to stencil indices.
GL_PIXEL_MAP_I_TO_R Maps color indices to red components.
GL_PIXEL_MAP_I_TO_G Maps color indices to green components.
GL_PIXEL_MAP_I_TO_B Maps color indices to blue components.
GL_PIXEL_MAP_I_TO_A Maps color indices to alpha components.
GL_PIXEL_MAP_R_TO_R Maps red components to red components.
GL_PIXEL_MAP_G_TO_G Maps green components to green components.
GL_PIXEL_MAP_B_TO_B Maps blue components to blue components.
GL_PIXEL_MAP_A_TO_A Maps alpha components to alpha components.
The entries in a map can be specified as single-precision floating-point
numbers, unsigned short integers, or unsigned long integers. Maps that
store color component values (all but GL_PIXEL_MAP_I_TO_I and
GL_PIXEL_MAP_S_TO_S) retain their values in floating-point format, with
unspecified mantissa and exponent sizes. Floating-point values specified
by glPixelMapfv are converted directly to the internal floating-point
format of these maps, then clamped to the range [0,1]. Unsigned integer
values specified by glPixelMapusv and glPixelMapuiv are converted linearly
such that the largest representable integer maps to 1.0, and zero maps to
0.0.
Maps that store indices, GL_PIXEL_MAP_I_TO_I and GL_PIXEL_MAP_S_TO_S,
retain their values in fixed-point format, with an unspecified number of
bits to the right of the binary point. Floating-point values specified by
glPixelMapfv are converted directly to the internal fixed-point format of
these maps. Unsigned integer values specified by glPixelMapusv and
glPixelMapuiv specify integer values, with all zeros to the right of the
binary point.
The table below shows the initial sizes and values for each of the maps.
Maps that are indexed by either color or stencil indices must have mapsize
= 2n for some n or results are undefined. The maximum allowable size for
each map depends on the implementation and can be determined by calling
glGet with argument GL_MAX_PIXEL_MAP_TABLE. The single maximum applies to
all maps, and it is at least 32.
--------------------------------------------------------------------------------------
| map | lookup index | lookup value | initial size | initial value |
--------------------------------------------------------------------------------------
|GL_PIXEL_MAP_I_TO_I | color index | color index | 1 | 0.0 |
|GL_PIXEL_MAP_S_TO_S | stencil index | stencil index | 1 | 0 |
|GL_PIXEL_MAP_I_TO_R | color index | R | 1 | 0.0 |
|GL_PIXEL_MAP_I_TO_G | color index | G | 1 | 0.0 |
|GL_PIXEL_MAP_I_TO_B | color index | B | 1 | 0.0 |
|GL_PIXEL_MAP_I_TO_A | color index | A | 1 | 0.0 |
|GL_PIXEL_MAP_R_TO_R | R | R | 1 | 0.0 |
|GL_PIXEL_MAP_G_TO_G | G | G | 1 | 0.0 |
|GL_PIXEL_MAP_B_TO_B | B | B | 1 | 0.0 |
|GL_PIXEL_MAP_A_TO_A | A | A | 1 | 0.0 |
--------------------------------------------------------------------------------------
Errors
GL_INVALID_ENUM is generated if map is not an accepted value.
GL_INVALID_VALUE is generated if mapsize is negative or larger than
GL_MAX_PIXEL_MAP_TABLE.
GL_INVALID_VALUE is generated if map is GL_PIXEL_MAP_I_TO_I,
GL_PIXEL_MAP_S_TO_S, GL_PIXEL_MAP_I_TO_R, GL_PIXEL_MAP_I_TO_G,
GL_PIXEL_MAP_I_TO_B, or GL_PIXEL_MAP_I_TO_A, and mapsize is not a power of
two.
GL_INVALID_OPERATION is generated if glPixelMap is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetPixelMap
glGet with argument GL_PIXEL_MAP_I_TO_I_SIZE
glGet with argument GL_PIXEL_MAP_S_TO_S_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_R_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_G_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_B_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_A_SIZE
glGet with argument GL_PIXEL_MAP_R_TO_R_SIZE
glGet with argument GL_PIXEL_MAP_G_TO_G_SIZE
glGet with argument GL_PIXEL_MAP_B_TO_B_SIZE
glGet with argument GL_PIXEL_MAP_A_TO_A_SIZE
glGet with argument GL_MAX_PIXEL_MAP_TABLE
See Also
glCopyPixels, glDrawPixels, glPixelStore, glPixelTransfer, glReadPixels,
glTexImage1D, glTexImage2D
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.85. glPixelStore ΓòÉΓòÉΓòÉ
OpenGL man pages
glPixelStore
Name
glPixelStoref, glPixelStorei - set pixel storage modes
C Specification
void glPixelStoref( GLenum pname,
GLfloat param )
void glPixelStorei( GLenum pname,
GLint param )
Parameters
pname Specifies the symbolic name of the parameter to be set. Six values
affect the packing of pixel data into memory: GL_PACK_SWAP_BYTES,
GL_PACK_LSB_FIRST, GL_PACK_ROW_LENGTH, GL_PACK_SKIP_PIXELS,
GL_PACK_SKIP_ROWS, and GL_PACK_ALIGNMENT. Six more affect the
unpacking of pixel data from memory: GL_UNPACK_SWAP_BYTES,
GL_UNPACK_LSB_FIRST, GL_UNPACK_ROW_LENGTH, GL_UNPACK_SKIP_PIXELS,
GL_UNPACK_SKIP_ROWS, and GL_UNPACK_ALIGNMENT.
param Specifies the value that pname is set to.
Description
glPixelStore sets pixel storage modes that affect the operation of
subsequent glDrawPixels and glReadPixels as well as the unpacking of
polygon stipple patterns (see glPolygonStipple), bitmaps (see glBitmap),
and texture patterns (see glTexImage1D and glTexImage2D).
pname is a symbolic constant indicating the parameter to be set, and param
is the new value. Six of the twelve storage parameters affect how pixel
data is returned to client memory, and are therefore significant only for
glReadPixels commands. They are as follows:
GL_PACK_SWAP_BYTES
If true, byte ordering for multibyte color components, depth
components, color indices, or stencil indices is reversed. That
is, if a four-byte component is made up of bytes b , b , b , b ,
0 1 2 3
it is stored in memory as b , b , b , b if GL_PACK_SWAP_BYTES is
3 2 1 0
true. GL_PACK_SWAP_BYTES has no effect on the memory order of
components within a pixel, only on the order of bytes within
components or indices. For example, the three components of a
GL_RGB format pixel are always stored with red first, green
second, and blue third, regardless of the value of
GL_PACK_SWAP_BYTES.
GL_PACK_LSB_FIRST
If true, bits are ordered within a byte from least significant to
most significant; otherwise, the first bit in each byte is the
most significant one. This parameter is significant for bitmap
data only.
GL_PACK_ROW_LENGTH
If greater than zero, GL_PACK_ROW_LENGTH defines the number of
pixels in a row. If the first pixel of a row is placed at
location p in memory, then the location of the first pixel of the
next row is obtained by skipping
k = nl if s >= a
snl
k = a/sΓòûceil( --- ) if s < a
a
components or indices, where n is the number of components or
indices in a pixel, l is the number of pixels in a row
(GL_PACK_ROW_LENGTH if it is greater than zero, the width
argument to the pixel routine otherwise), a is the value of
GL_PACK_ALIGNMENT, and s is the size, in bytes, of a single
component (if a<s, then it is as if a=s). In the case of 1-bit
values, the location of the next row is obtained by skipping
nl
k = 8aΓòûceil( -- )
8a
components or indices.
The word component in this description refers to the nonindex
values red, green, blue, alpha, and depth. Storage format
GL_RGB, for example, has three components per pixel: first red,
then green, and finally blue.
GL_PACK_SKIP_PIXELS and GL_PACK_SKIP_ROWS
These values are provided as a convenience to the programmer;
they provide no functionality that cannot be duplicated simply by
incrementing the pointer passed to glReadPixels. Setting
GL_PACK_SKIP_PIXELS to i is equivalent to incrementing the
pointer by in components or indices, where n is the number of
components or indices in each pixel. Setting GL_PACK_SKIP_ROWS
to j is equivalent to incrementing the pointer by jk components
or indices, where k is the number of components or indices per
row, as computed above in the GL_PACK_ROW_LENGTH section.
GL_PACK_ALIGNMENT
Specifies the alignment requirements for the start of each pixel
row in memory. The allowable values are 1 (byte-alignment), 2
(rows aligned to even-numbered bytes), 4 (word alignment), and 8
(rows start on double-word boundaries).
The other six of the twelve storage parameters affect how pixel data is
read from client memory. These values are significant for glDrawPixels,
glTexImage1D, glTexImage2D, glBitmap, and glPolygonStipple. They are as
follows:
GL_UNPACK_SWAP_BYTES
If true, byte ordering for multibyte color components, depth
components, color indices, or stencil indices is reversed. That is,
if a four-byte component is made up of bytes b , b , b , b , it is
0 1 2 3
taken from memory as b , b , b , b if GL_UNPACK_SWAP_BYTES is true.
3 2 1 0
GL_UNPACK_SWAP_BYTES has no effect on the memory order of components
within a pixel, only on the order of bytes within components or
indices. For example, the three components of a GL_RGB format pixel
are always stored with red first, green second, and blue third,
regardless of the value of GL_UNPACK_SWAP_BYTES.
GL_UNPACK_LSB_FIRST
If true, bits are ordered within a byte from least significant to most
significant; otherwise, the first bit in each byte is the most
significant one. This is significant for bitmap data only.
GL_UNPACK_ROW_LENGTH
If greater than zero, GL_UNPACK_ROW_LENGTH defines the number of
pixels in a row. If the first pixel of a row is placed at location p
in memory, then the location of the first pixel of the next row is
obtained by skipping
k = nl if s >= a
snl
k = a/sΓòûceil( --- ) if s < a
a
components or indices, where n is the number of components or indices
in a pixel, l is the number of pixels in a row (GL_UNPACK_ROW_LENGTH
if it is greater than zero, the width argument to the pixel routine
otherwise), a is the value of GL_UNPACK_ALIGNMENT, and s is the size,
in bytes, of a single component (if a<s, then it is as if a=s). In
the case of 1-bit values, the location of the next row is obtained by
skipping
nl
k = 8aΓòûceil( -- )
8a
components or indices.
The word component in this description refers to the nonindex values
red, green, blue, alpha, and depth. Storage format GL_RGB, for
example, has three components per pixel: first red, then green, and
finally blue.
GL_UNPACK_SKIP_PIXELS and GL_UNPACK_SKIP_ROWS
These values are provided as a convenience to the programmer; they
provide no functionality that cannot be duplicated simply by
incrementing the pointer passed to glDrawPixels, glTexImage1D,
glTexImage2D, glBitmap, or glPolygonStipple. Setting
GL_UNPACK_SKIP_PIXELS to i is equivalent to incrementing the pointer
by in components or indices, where n is the number of components or
indices in each pixel. Setting GL_UNPACK_SKIP_ROWS to j is equivalent
to incrementing the pointer by jk components or indices, where k is
the number of components or indices per row, as computed above in the
GL_UNPACK_ROW_LENGTH section.
GL_UNPACK_ALIGNMENT
Specifies the alignment requirements for the start of each pixel row
in memory. The allowable values are 1 (byte-alignment), 2 (rows
aligned to even-numbered bytes), 4 (word alignment), and 8 (rows start
on double-word boundaries).
The following table gives the type, initial value, and range of valid
values for each of the storage parameters that can be set with
glPixelStore.
-----------------------------------------------------------------
| parameter name | type | initial value | valid range |
-----------------------------------------------------------------
| GL_PACK_SWAP_BYTES | Boolean | false | true or false |
| GL_PACK_LSB_FIRST | Boolean | false | true or false |
| GL_PACK_ROW_LENGTH | integer | 0 | [0,oo) |
| GL_PACK_SKIP_ROWS | integer | 0 | [0,oo) |
| GL_PACK_SKIP_PIXELS | integer | 0 | [0,oo) |
| GL_PACK_ALIGNMENT | integer | 4 | 1, 2, 4, or 8 |
|----------------------------------------------------------------|
|GL_UNPACK_SWAP_BYTES | Boolean | false | true or false |
| GL_UNPACK_LSB_FIRST | Boolean | false | true or false |
|GL_UNPACK_ROW_LENGTH | integer | 0 | [0,oo) |
| GL_UNPACK_SKIP_ROWS | integer | 0 | [0,oo) |
|GL_UNPACK_SKIP_PIXELS | integer | 0 | [0,oo) |
| GL_UNPACK_ALIGNMENT | integer | 4 | 1, 2, 4, or 8 |
-----------------------------------------------------------------
glPixelStoref can be used to set any pixel store parameter. If the
parameter type is Boolean, then if param is 0.0, the parameter is false;
otherwise it is set to true. If pname is a integer type parameter, param
is rounded to the nearest integer.
Likewise, glPixelStorei can also be used to set any of the pixel store
parameters. Boolean parameters are set to false if param is 0 and true
otherwise. param is converted to floating point before being assigned to
real-valued parameters.
Notes
The pixel storage modes in effect when glDrawPixels, glReadPixels,
glTexImage1D, glTexImage2D, glBitmap, or glPolygonStipple is placed in a
display list control the interpretation of memory data. The pixel storage
modes in effect when a display list is executed are not significant.
Errors
GL_INVALID_ENUM is generated if pname is not an accepted value.
GL_INVALID_VALUE is generated if a negative row length, pixel skip, or row
skip value is specified, or if alignment is specified as other than 1, 2,
4, or 8.
GL_INVALID_OPERATION is generated if glPixelStore is called between a call
to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_PACK_SWAP_BYTES
glGet with argument GL_PACK_LSB_FIRST
glGet with argument GL_PACK_ROW_LENGTH
glGet with argument GL_PACK_SKIP_ROWS
glGet with argument GL_PACK_SKIP_PIXELS
glGet with argument GL_PACK_ALIGNMENT
glGet with argument GL_UNPACK_SWAP_BYTES
glGet with argument GL_UNPACK_LSB_FIRST
glGet with argument GL_UNPACK_ROW_LENGTH
glGet with argument GL_UNPACK_SKIP_ROWS
glGet with argument GL_UNPACK_SKIP_PIXELS
glGet with argument GL_UNPACK_ALIGNMENT
See Also
glBitmap, glDrawPixels, glPixelMap, glPixelTransfer, glPixelZoom,
glPolygonStipple, glReadPixels, glTexImage1D, glTexImage2D
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
Look here for legal stuff: Legal
ΓòÉΓòÉΓòÉ 3.86. glPixelTransfer ΓòÉΓòÉΓòÉ
OpenGL man pages
glPixelTransfer
Name
glPixelTransferf, glPixelTransferi - set pixel transfer modes
C Specification
void glPixelTransferf( GLenum pname,
GLfloat param )
void glPixelTransferi( GLenum pname,
GLint param )
Parameters
pname Specifies the symbolic name of the pixel transfer parameter to be
set. Must be one of the following: GL_MAP_COLOR, GL_MAP_STENCIL,
GL_INDEX_SHIFT, GL_INDEX_OFFSET, GL_RED_SCALE, GL_RED_BIAS,
GL_GREEN_SCALE, GL_GREEN_BIAS, GL_BLUE_SCALE, GL_BLUE_BIAS,
GL_ALPHA_SCALE, GL_ALPHA_BIAS, GL_DEPTH_SCALE, or GL_DEPTH_BIAS.
param Specifies the value that pname is set to.
Description
glPixelTransfer sets pixel transfer modes that affect the operation of
subsequent glDrawPixels, glReadPixels, glCopyPixels, glTexImage1D, and
glTexImage2D commands. The algorithms that are specified by pixel transfer
modes operate on pixels after they are read from the frame buffer
(glReadPixels and glCopyPixels) or unpacked from client memory
(glDrawPixels, glTexImage1D, and glTexImage2D). Pixel transfer operations
happen in the same order, and in the same manner, regardless of the command
that resulted in the pixel operation. Pixel storage modes (see
glPixelStore) control the unpacking of pixels being read from client
memory, and the packing of pixels being written back into client memory.
Pixel transfer operations handle four fundamental pixel types: color, color
index, depth, and stencil. Color pixels are made up of four floating-point
values with unspecified mantissa and exponent sizes, scaled such that 0.0
represents zero intensity and 1.0 represents full intensity. Color indices
comprise a single fixed-point value, with unspecified precision to the
right of the binary point. Depth pixels comprise a single floating-point
value, with unspecified mantissa and exponent sizes, scaled such that 0.0
represents the minimum depth buffer value, and 1.0 represents the maximum
depth buffer value. Finally, stencil pixels comprise a single fixed-point
value, with unspecified precision to the right of the binary point.
The pixel transfer operations performed on the four basic pixel types are
as follows:
Color Each of the four color components is multiplied by a scale
factor, then added to a bias factor. That is, the red
component is multiplied by GL_RED_SCALE, then added to
GL_RED_BIAS; the green component is multiplied by
GL_GREEN_SCALE, then added to GL_GREEN_BIAS; the blue component
is multiplied by GL_BLUE_SCALE, then added to GL_BLUE_BIAS; and
the alpha component is multiplied by GL_ALPHA_SCALE, then added
to GL_ALPHA_BIAS. After all four color components are scaled
and biased, each is clamped to the range [0,1]. All color
scale and bias values are specified with glPixelTransfer.
If GL_MAP_COLOR is true, each color component is scaled by the
size of the corresponding color-to-color map, then replaced by
the contents of that map indexed by the scaled component. That
is, the red component is scaled by GL_PIXEL_MAP_R_TO_R_SIZE,
then replaced by the contents of GL_PIXEL_MAP_R_TO_R indexed by
itself. The green component is scaled by
GL_PIXEL_MAP_G_TO_G_SIZE, then replaced by the contents of
GL_PIXEL_MAP_G_TO_G indexed by itself. The blue component is
scaled by GL_PIXEL_MAP_B_TO_B_SIZE, then replaced by the
contents of GL_PIXEL_MAP_B_TO_B indexed by itself. And the
alpha component is scaled by GL_PIXEL_MAP_A_TO_A_SIZE, then
replaced by the contents of GL_PIXEL_MAP_A_TO_A indexed by
itself. All components taken from the maps are then clamped to
the range [0,1]. GL_MAP_COLOR is specified with
glPixelTransfer. The contents of the various maps are
specified with glPixelMap.
Color index Each color index is shifted left by GL_INDEX_SHIFT bits,
filling with zeros any bits beyond the number of fraction bits
carried by the fixed-point index. If GL_INDEX_SHIFT is
negative, the shift is to the right, again zero filled. Then
GL_INDEX_OFFSET is added to the index. GL_INDEX_SHIFT and
GL_INDEX_OFFSET are specified with glPixelTransfer.
From this point, operation diverges depending on the required
format of the resulting pixels. If the resulting pixels are to
be written to a color index buffer, or if they are being read
back to client memory in GL_COLOR_INDEX format, the pixels
continue to be treated as indices. If GL_MAP_COLOR is true,
each index is masked by 2n - 1, where n is
GL_PIXEL_MAP_I_TO_I_SIZE, then replaced by the contents of
GL_PIXEL_MAP_I_TO_I indexed by the masked value. GL_MAP_COLOR
is specified with glPixelTransfer. The contents of the index
map are specified with glPixelMap.
If the resulting pixels are to be written to an RGBA color
buffer, or if they are being read back to client memory in a
format other than GL_COLOR_INDEX, the pixels are converted from
indices to colors by referencing the four maps
GL_PIXEL_MAP_I_TO_R, GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B,
and GL_PIXEL_MAP_I_TO_A. Before being dereferenced, the index
is masked by 2n - 1, where n is GL_PIXEL_MAP_I_TO_R_SIZE for
the red map, GL_PIXEL_MAP_I_TO_G_SIZE for the green map,
GL_PIXEL_MAP_I_TO_B_SIZE for the blue map, and
GL_PIXEL_MAP_I_TO_A_SIZE for the alpha map. All components
taken from the maps are then clamped to the range [0,1]. The
contents of the four maps are specified with glPixelMap.
Depth Each depth value is multiplied by GL_DEPTH_SCALE, added to
GL_DEPTH_BIAS, then clamped to the range [0,1].
Stencil Each index is shifted GL_INDEX_SHIFT bits just as a color index
is, then added to GL_INDEX_OFFSET. If GL_MAP_STENCIL is true,
each index is masked by 2n - 1, where n is
GL_PIXEL_MAP_S_TO_S_SIZE, then replaced by the contents of
GL_PIXEL_MAP_S_TO_S indexed by the masked value.
The following table gives the type, initial value, and range of valid
values for each of the pixel transfer parameters that are set with
glPixelTransfer.
---------------------------------------------------------
| pname | type | initial value | valid range |
---------------------------------------------------------
| GL_MAP_COLOR | Boolean | false | true/false |
|GL_MAP_STENCIL | Boolean | false | true/false |
|GL_INDEX_SHIFT | integer | 0 | (-oo,oo) |
|GL_INDEX_OFFSET | integer | 0 | (-oo,oo) |
| GL_RED_SCALE | float | 1.0 | (-oo,oo) |
|GL_GREEN_SCALE | float | 1.0 | (-oo,oo) |
| GL_BLUE_SCALE | float | 1.0 | (-oo,oo) |
|GL_ALPHA_SCALE | float | 1.0 | (-oo,oo) |
|GL_DEPTH_SCALE | float | 1.0 | (-oo,oo) |
| GL_RED_BIAS | float | 0.0 | (-oo,oo) |
| GL_GREEN_BIAS | float | 0.0 | (-oo,oo) |
| GL_BLUE_BIAS | float | 0.0 | (-oo,oo) |
| GL_ALPHA_BIAS | float | 0.0 | (-oo,oo) |
| GL_DEPTH_BIAS | float | 0.0 | (-oo,oo) |
---------------------------------------------------------
glPixelTransferf can be used to set any pixel transfer parameter. If the
parameter type is Boolean, 0.0 implies false and any other value implies
true. If pname is an integer parameter, param is rounded to the nearest
integer.
Likewise, glPixelTransferi can also be used to set any of the pixel
transfer parameters. Boolean parameters are set to false if param is 0 and
true otherwise. param is converted to floating point before being assigned
to real-valued parameters.
Notes
If a glDrawPixels, glReadPixels, glCopyPixels, glTexImage1D, or
glTexImage2D command is placed in a display list (see glNewList and
glCallList), the pixel transfer mode settings in effect when the display
list is executed are the ones that are used. They may be different from
the settings when the command was compiled into the display list.
Errors
GL_INVALID_ENUM is generated if pname is not an accepted value.
GL_INVALID_OPERATION is generated if glPixelTransfer is called between a
call to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_MAP_COLOR
glGet with argument GL_MAP_STENCIL
glGet with argument GL_INDEX_SHIFT
glGet with argument GL_INDEX_OFFSET
glGet with argument GL_RED_SCALE
glGet with argument GL_RED_BIAS
glGet with argument GL_GREEN_SCALE
glGet with argument GL_GREEN_BIAS
glGet with argument GL_BLUE_SCALE
glGet with argument GL_BLUE_BIAS
glGet with argument GL_ALPHA_SCALE
glGet with argument GL_ALPHA_BIAS
glGet with argument GL_DEPTH_SCALE
glGet with argument GL_DEPTH_BIAS
See Also
glCallList, glCopyPixels, glDrawPixels, glNewList, glPixelMap,
glPixelStore, glPixelZoom, glReadPixels, glTexImage1D, glTexImage2D
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
Look here for legal stuff: Legal
ΓòÉΓòÉΓòÉ 3.87. glPixelZoom ΓòÉΓòÉΓòÉ
OpenGL man pages
glPixelZoom
Name
glPixelZoom - specify the pixel zoom factors
C Specification
void glPixelZoom( GLfloat xfactor,
GLfloat yfactor )
Parameters
xfactor, yfactor Specify the x and y zoom factors for pixel write
operations.
Description
glPixelZoom specifies values for the x and y zoom factors. During the
execution of glDrawPixels or glCopyPixels, if (xr, yr) is the current
raster position, and a given element is in the mth row and nth column of
the pixel rectangle, then pixels whose centers are in the rectangle with
corners at
(xr + nΓòûxfactor, yr + mΓòûyfactor)
(xr + (n+1)Γòûxfactor, yr + (m+1)Γòûyfactor)
are candidates for replacement. Any pixel whose center lies on the bottom
or left edge of this rectangular region is also modified.
Pixel zoom factors are not limited to positive values. Negative zoom
factors reflect the resulting image about the current raster position.
Errors
GL_INVALID_OPERATION is generated if glPixelZoom is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_ZOOM_X
glGet with argument GL_ZOOM_Y
See Also
glCopyPixels, glDrawPixels
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ΓòÉΓòÉΓòÉ 3.88. glPointSize ΓòÉΓòÉΓòÉ
OpenGL man pages
glPointSize
Name
glPointSize - specify the diameter of rasterized points
C Specification
void glPointSize( GLfloat size )
Parameters
size Specifies the diameter of rasterized points. The default is 1.0.
Description
glPointSize specifies the rasterized diameter of both aliased and
antialiased points. Using a point size other than 1.0 has different
effects, depending on whether point antialiasing is enabled. Point
antialiasing is controlled by calling glEnable and glDisable with argument
GL_POINT_SMOOTH.
If point antialiasing is disabled, the actual size is determined by
rounding the supplied size to the nearest integer. (If the rounding
results in the value 0, it is as if the point size were 1.) If the rounded
size is odd, then the center point (x, y) of the pixel fragment that
represents the point is computed as
( floor(x )+.5, floor(y )+.5 )
w w
where w subscripts indicate window coordinates. All pixels that lie within
the square grid of the rounded size centered at (x, y) make up the
fragment. If the size is even, the center point is
( floor(x +.5), floor(y +.5) )
w w
and the rasterized fragment's centers are the half-integer window
coordinates within the square of the rounded size centered at (x, y). All
pixel fragments produced in rasterizing a nonantialiased point are assigned
the same associated data, that of the vertex corresponding to the point.
If antialiasing is enabled, then point rasterization produces a fragment
for each pixel square that intersects the region lying within the circle
having diameter equal to the current point size and centered at the point's
(x , y ). The coverage value for each fragment is the window coordinate
w w
area of the intersection of the circular region with the corresponding
pixel square. This value is saved and used in the final rasterization
step. The data associated with each fragment is the data associated with
the point being rasterized.
Not all sizes are supported when point antialiasing is enabled. If an
unsupported size is requested, the nearest supported size is used. Only
size 1.0 is guaranteed to be supported; others depend on the
implementation. The range of supported sizes and the size difference
between supported sizes within the range can be queried by calling glGet
with arguments GL_POINT_SIZE_RANGE and GL_POINT_SIZE_GRANULARITY.
Notes
The point size specified by glPointSize is always returned when
GL_POINT_SIZE is queried. Clamping and rounding for aliased and
antialiased points have no effect on the specified value.
Non-antialiased point size may be clamped to an implementation-dependent
maximum. Although this maximum cannot be queried, it must be no less than
the maximum value for antialiased points, rounded to the nearest integer
value.
Errors
GL_INVALID_VALUE is generated if size is less than or equal to zero.
GL_INVALID_OPERATION is generated if glPointSize is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_POINT_SIZE
glGet with argument GL_POINT_SIZE_RANGE
glGet with argument GL_POINT_SIZE_GRANULARITY
glIsEnabled with argument GL_POINT_SMOOTH
See Also
glEnable, glPointSmooth
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ΓòÉΓòÉΓòÉ 3.89. glPolygonMode ΓòÉΓòÉΓòÉ
OpenGL man pages
glPolygonMode
Name
glPolygonMode - select a polygon rasterization mode
C Specification
void glPolygonMode( GLenum face,
GLenum mode )
Parameters
face Specifies the polygons that mode applies to. Must be GL_FRONT for
front-facing polygons, GL_BACK for back-facing polygons, or
GL_FRONT_AND_BACK for front- and back-facing polygons.
mode Specifies the way polygons will be rasterized. Accepted values are
GL_POINT, GL_LINE, and GL_FILL. The default is GL_FILL for both
front- and back-facing polygons.
Description
glPolygonMode controls the interpretation of polygons for rasterization.
face describes which polygons mode applies to: front-facing polygons
(GL_FRONT), back-facing polygons (GL_BACK), or both (GL_FRONT_AND_BACK).
The polygon mode affects only the final rasterization of polygons. In
particular, a polygon's vertices are lit and the polygon is clipped and
possibly culled before these modes are applied.
Three modes are defined and can be specified in mode:
GL_POINT Polygon vertices that are marked as the start of a boundary
edge are drawn as points. Point attributes such as
GL_POINT_SIZE and GL_POINT_SMOOTH control the rasterization
of the points. Polygon rasterization attributes other than
GL_POLYGON_MODE have no effect.
GL_LINE Boundary edges of the polygon are drawn as line segments.
They are treated as connected line segments for line
stippling; the line stipple counter and pattern are not reset
between segments (see glLineStipple). Line attributes such
as GL_LINE_WIDTH and GL_LINE_SMOOTH control the rasterization
of the lines. Polygon rasterization attributes other than
GL_POLYGON_MODE have no effect.
GL_FILL The interior of the polygon is filled. Polygon attributes
such as GL_POLYGON_STIPPLE and GL_POLYGON_SMOOTH control the
rasterization of the polygon.
Examples
To draw a surface with filled back-facing polygons and outlined front-
facing polygons, call glPolygonMode(GL_FRONT, GL_LINE);
Notes
Vertices are marked as boundary or nonboundary with an edge flag. Edge
flags are generated internally by the GL when it decomposes polygons, and
they can be set explicitly using glEdgeFlag.
Errors
GL_INVALID_ENUM is generated if either face or mode is not an accepted
value.
GL_INVALID_OPERATION is generated if glPolygonMode is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_POLYGON_MODE
See Also
glBegin, glEdgeFlag, glLineStipple, glLineWidth, glPointSize,
glPolygonStipple
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ΓòÉΓòÉΓòÉ 3.90. glPolygonStipple ΓòÉΓòÉΓòÉ
OpenGL man pages
glPolygonStipple
Name
glPolygonStipple - set the polygon stippling pattern
C Specification
void glPolygonStipple( const GLubyte *mask )
Parameters
mask Specifies a pointer to a 32x32 stipple pattern that will be unpacked
from memory in the same way that glDrawPixels unpacks pixels.
Description
Polygon stippling, like line stippling (see glLineStipple), masks out
certain fragments produced by rasterization, creating a pattern. Stippling
is independent of polygon antialiasing.
mask is a pointer to a 32x32 stipple pattern that is stored in memory just
like the pixel data supplied to a glDrawPixels with height and width both
equal to 32, a pixel format of GL_COLOR_INDEX, and data type of GL_BITMAP.
That is, the stipple pattern is represented as a 32x32 array of 1-bit color
indices packed in unsigned bytes. glPixelStore parameters like
GL_UNPACK_SWAP_BYTES and GL_UNPACK_LSB_FIRST affect the assembling of the
bits into a stipple pattern. Pixel transfer operations (shift, offset,
pixel map) are not applied to the stipple image, however.
Polygon stippling is enabled and disabled with glEnable and glDisable,
using argument GL_POLYGON_STIPPLE. If enabled, a rasterized polygon
fragment with window coordinates x and y is sent to the next stage of the
w w
GL if and only if the (x mod 32)th bit is the (y mod 32)th row of the
w w
stipple pattern is one. When polygon stippling is disabled, it is as if
the stipple pattern were all ones.
Errors
GL_INVALID_OPERATION is generated if glPolygonStipple is executed between
the execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetPolygonStipple
glIsEnabled with argument GL_POLYGON_STIPPLE
See Also
glDrawPixels, glLineStipple, glPixelStore, glPixelTransfer
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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.91. glPushAttrib ΓòÉΓòÉΓòÉ
OpenGL man pages
glPushAttrib
Name
glPushAttrib, glPopAttrib - push and pop the attribute stack
C Specification
void glPushAttrib( GLbitfield mask )
Parameters
mask Specifies a mask that indicates which attributes to save. Values for
mask are listed in the table below.
C Specification
void glPopAttrib( void )
Description
glPushAttrib takes one argument, a mask that indicates which groups of
state variables to save on the attribute stack. Symbolic constants are
used to set bits in the mask. mask is typically constructed by ORing
several of these constants together. The special mask GL_ALL_ATTRIB_BITS
can be used to save all stackable states.
The symbolic mask constants and their associated GL state are as follows
(the second column lists which attributes are saved):
GL_ACCUM_BUFFER_BIT Accumulation buffer clear value
GL_COLOR_BUFFER_BIT GL_ALPHA_TEST enable bit
Alpha test function and reference value
GL_BLEND enable bit
Blending source and destination functions
GL_DITHER enable bit
GL_DRAW_BUFFER setting
GL_LOGIC_OP enable bit
Logic op function
Color mode and index mode clear values
Color mode and index mode writemasks
GL_CURRENT_BIT Current RGBA color
Current color index
Current normal vector
Current texture coordinates
Current raster position
GL_CURRENT_RASTER_POSITION_VALID flag
RGBA color associated with current raster position
Color index associated with current raster position
Texture coordinates associated with current raster position
GL_EDGE_FLAG flag
GL_DEPTH_BUFFER_BIT GL_DEPTH_TEST enable bit
Depth buffer test function
Depth buffer clear value
GL_DEPTH_WRITEMASK enable bit
GL_ENABLE_BIT GL_ALPHA_TEST flag
GL_AUTO_NORMAL flag
GL_BLEND flag
Enable bits for the user-definable clipping planes
GL_COLOR_MATERIAL
GL_CULL_FACE flag
GL_DEPTH_TEST flag
GL_DITHER flag
GL_FOG flag
GL_LIGHTi where 0 <= i<GL_MAX_LIGHTS
GL_LIGHTING flag
GL_LINE_SMOOTH flag
GL_LINE_STIPPLE flag
GL_LOGIC_OP flag
GL_MAP1_x where x is a map type
GL_MAP2_x where x is a map type
GL_NORMALIZE flag
GL_POINT_SMOOTH flag
GL_POLYGON_SMOOTH flag
GL_POLYGON_STIPPLE flag
GL_SCISSOR_TEST flag
GL_STENCIL_TEST flag
GL_TEXTURE_1D flag
GL_TEXTURE_2D flag
Flags GL_TEXTURE_GEN_x where x is S, T, R, or Q
GL_EVAL_BIT GL_MAP1_x enable bits, where x is a map type
GL_MAP2_x enable bits, where x is a map type
1-D grid endpoints and divisions
2-D grid endpoints and divisions
GL_AUTO_NORMAL enable bit
GL_FOG_BIT GL_FOG enable flag
Fog color
Fog density
Linear fog start
Linear fog end
Fog index
GL_FOG_MODE value
GL_HINT_BIT GL_PERSPECTIVE_CORRECTION_HINT setting
GL_POINT_SMOOTH_HINT setting
GL_LINE_SMOOTH_HINT setting
GL_POLYGON_SMOOTH_HINT setting
GL_FOG_HINT setting
GL_LIGHTING_BIT GL_COLOR_MATERIAL enable bit
GL_COLOR_MATERIAL_FACE value
Color material parameters that are tracking the current color
Ambient scene color
GL_LIGHT_MODEL_LOCAL_VIEWER value
GL_LIGHT_MODEL_TWO_SIDE setting
GL_LIGHTING enable bit
Enable bit for each light
Ambient, diffuse, and specular intensity for each light
Direction, position, exponent, and cutoff angle for each light
Constant, linear, and quadratic attenuation factors for each light
Ambient, diffuse, specular, and emissive color for each material
Ambient, diffuse, and specular color indices for each material
Specular exponent for each material
GL_SHADE_MODEL setting
GL_LINE_BIT GL_LINE_SMOOTH flag
GL_LINE_STIPPLE enable bit
Line stipple pattern and repeat counter
Line width
GL_LIST_BIT GL_LIST_BASE setting
GL_PIXEL_MODE_BIT GL_RED_BIAS and GL_RED_SCALE settings
GL_GREEN_BIAS and GL_GREEN_SCALE values
GL_BLUE_BIAS and GL_BLUE_SCALE
GL_ALPHA_BIAS and GL_ALPHA_SCALE
GL_DEPTH_BIAS and GL_DEPTH_SCALE
GL_INDEX_OFFSET and GL_INDEX_SHIFT values
GL_MAP_COLOR and GL_MAP_STENCIL flags
GL_ZOOM_X and GL_ZOOM_Y factors
GL_READ_BUFFER setting
GL_POINT_BIT GL_POINT_SMOOTH flag
Point size
GL_POLYGON_BIT GL_CULL_FACE enable bit
GL_CULL_FACE_MODE value
GL_FRONT_FACE indicator
GL_POLYGON_MODE setting
GL_POLYGON_SMOOTH flag
GL_POLYGON_STIPPLE enable bit
GL_POLYGON_STIPPLE_BIT Polygon stipple image
GL_SCISSOR_BIT GL_SCISSOR_TEST flag
Scissor box
GL_STENCIL_BUFFER_BIT GL_STENCIL_TEST enable bit
Stencil function and reference value
Stencil value mask
Stencil fail, pass, and depth buffer pass actions
Stencil buffer clear value
Stencil buffer writemask
GL_TEXTURE_BIT Enable bits for the four texture coordinates
Border color for each texture image
Minification function for each texture image
Magnification function for each texture image
Texture coordinates and wrap mode for each texture image
Color and mode for each texture environment
Enable bits GL_TEXTURE_GEN_x, x is S, T, R, and Q
GL_TEXTURE_GEN_MODE setting for S, T, R, and Q
glTexGen plane equations for S, T, R, and Q
GL_TRANSFORM_BIT Coefficients of the six clipping planes
Enable bits for the user-definable clipping planes
GL_MATRIX_MODE value
GL_NORMALIZE flag
GL_VIEWPORT_BIT Depth range (near and far)
Viewport origin and extent
glPopAttrib restores the values of the state variables saved with the last
glPushAttrib command. Those not saved are left unchanged.
It is an error to push attributes onto a full stack, or to pop attributes
off an empty stack. In either case, the error flag is set and no other
change is made to GL state.
Initially, the attribute stack is empty.
Notes
Not all values for GL state can be saved on the attribute stack. For
example, pixel pack and unpack state, render mode state, and select and
feedback state cannot be saved.
The depth of the attribute stack depends on the implementation, but it must
be at least 16.
Errors
GL_STACK_OVERFLOW is generated if glPushAttrib is called while the
attribute stack is full.
GL_STACK_UNDERFLOW is generated if glPopAttrib is called while the
attribute stack is empty.
GL_INVALID_OPERATION is generated if glPushAttrib or glPopAttrib is
executed between the execution of glBegin and the corresponding execution
of glEnd.
Associated Gets
glGet with argument GL_ATTRIB_STACK_DEPTH.
glGet with argument GL_MAX_ATTRIB_STACK_DEPTH.
See Also
glGet, glGetClipPlane, glGetError, glGetLight, glGetMap, glGetMaterial,
glGetPixelMap, glGetPolygonStipple, glGetString, glGetTexEnv, glGetTexGen,
glGetTexImage, glGetTexLevelParameter, glGetTexParameter, glIsEnabled
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.92. glPushMatrix ΓòÉΓòÉΓòÉ
OpenGL man pages
glPushMatrix
Name
glPushMatrix, glPopMatrix - push and pop the current matrix stack
C Specification
void glPushMatrix( void )
C Specification
void glPopMatrix( void )
Description
There is a stack of matrices for each of the matrix modes. In GL_MODELVIEW
mode, the stack depth is at least 32. In the other two modes,
GL_PROJECTION and GL_TEXTURE, the depth is at least 2. The current matrix
in any mode is the matrix on the top of the stack for that mode.
glPushMatrix pushes the current matrix stack down by one, duplicating the
current matrix. That is, after a glPushMatrix call, the matrix on the top
of the stack is identical to the one below it.
glPopMatrix pops the current matrix stack, replacing the current matrix
with the one below it on the stack.
Initially, each of the stacks contains one matrix, an identity matrix.
It is an error to push a full matrix stack, or to pop a matrix stack that
contains only a single matrix. In either case, the error flag is set and
no other change is made to GL state.
Errors
GL_STACK_OVERFLOW is generated if glPushMatrix is called while the current
matrix stack is full.
GL_STACK_UNDERFLOW is generated if glPopMatrix is called while the current
matrix stack contains only a single matrix.
GL_INVALID_OPERATION is generated if glPushMatrix or glPopMatrix is
executed between the execution of glBegin and the corresponding execution
of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
glGet with argument GL_MODELVIEW_STACK_DEPTH
glGet with argument GL_PROJECTION_STACK_DEPTH
glGet with argument GL_TEXTURE_STACK_DEPTH
glGet with argument GL_MAX_MODELVIEW_STACK_DEPTH
glGet with argument GL_MAX_PROJECTION_STACK_DEPTH
glGet with argument GL_MAX_TEXTURE_STACK_DEPTH
See Also
glFrustum, glLoadIdentity, glLoadMatrix, glMatrixMode, glMultMatrix,
glOrtho, glRotate, glScale, glTranslate, glViewport
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.93. glPushName ΓòÉΓòÉΓòÉ
OpenGL man pages
glPushName
Name
glPushName, glPopName - push and pop the name stack
C Specification
void glPushName( GLuint name )
Parameters
name Specifies a name that will be pushed onto the name stack.
C Specification
void glPopName( void )
Description
The name stack is used during selection mode to allow sets of rendering
commands to be uniquely identified. It consists of an ordered set of
unsigned integers. glPushName causes name to be pushed onto the name
stack, which is initially empty. glPopName pops one name off the top of
the stack.
It is an error to push a name onto a full stack, or to pop a name off an
empty stack. It is also an error to manipulate the name stack between the
execution of glBegin and the corresponding execution of glEnd. In any of
these cases, the error flag is set and no other change is made to GL state.
The name stack is always empty while the render mode is not GL_SELECT.
Calls to glPushName or glPopName while the render mode is not GL_SELECT are
ignored.
Errors
GL_STACK_OVERFLOW is generated if glPushName is called while the name stack
is full.
GL_STACK_UNDERFLOW is generated if glPopName is called while the name stack
is empty.
GL_INVALID_OPERATION is generated if glPushName or glPopName is executed
between a call to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_NAME_STACK_DEPTH
glGet with argument GL_MAX_NAME_STACK_DEPTH
See Also
glInitNames, glLoadName, glRenderMode, glSelectBuffer
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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.94. glRasterPos ΓòÉΓòÉΓòÉ
OpenGL man pages
glRasterPos
Name
glRasterPos2d, glRasterPos2f, glRasterPos2i, glRasterPos2s, glRasterPos3d,
glRasterPos3f, glRasterPos3i, glRasterPos3s, glRasterPos4d, glRasterPos4f,
glRasterPos4i, glRasterPos4s, glRasterPos2dv, glRasterPos2fv,
glRasterPos2iv, glRasterPos2sv, glRasterPos3dv, glRasterPos3fv,
glRasterPos3iv, glRasterPos3sv, glRasterPos4dv, glRasterPos4fv,
glRasterPos4iv, glRasterPos4sv - specify the raster position for pixel
operations
C Specification
void glRasterPos2d( GLdouble x,
GLdouble y )
void glRasterPos2f( GLfloat x,
GLfloat y )
void glRasterPos2i( GLint x,
GLint y )
void glRasterPos2s( GLshort x,
GLshort y )
void glRasterPos3d( GLdouble x,
GLdouble y,
GLdouble z )
void glRasterPos3f( GLfloat x,
GLfloat y,
GLfloat z )
void glRasterPos3i( GLint x,
GLint y,
GLint z )
void glRasterPos3s( GLshort x,
GLshort y,
GLshort z )
void glRasterPos4d( GLdouble x,
GLdouble y,
GLdouble z,
GLdouble w )
void glRasterPos4f( GLfloat x,
GLfloat y,
GLfloat z,
GLfloat w )
void glRasterPos4i( GLint x,
GLint y,
GLint z,
GLint w )
void glRasterPos4s( GLshort x,
GLshort y,
GLshort z,
GLshort w )
Parameters
x, y, z, w
Specify the x, y, z, and w object coordinates (if present) for the
raster position.
C Specification
void glRasterPos2dv( const GLdouble *v )
void glRasterPos2fv( const GLfloat *v )
void glRasterPos2iv( const GLint *v )
void glRasterPos2sv( const GLshort *v )
void glRasterPos3dv( const GLdouble *v )
void glRasterPos3fv( const GLfloat *v )
void glRasterPos3iv( const GLint *v )
void glRasterPos3sv( const GLshort *v )
void glRasterPos4dv( const GLdouble *v )
void glRasterPos4fv( const GLfloat *v )
void glRasterPos4iv( const GLint *v )
void glRasterPos4sv( const GLshort *v )
v Specifies a pointer to an array of two, three, or four elements,
specifying x, y, z, and w coordinates, respectively.
Description
The GL maintains a 3-D position in window coordinates. This position,
called the raster position, is maintained with subpixel accuracy. It is
used to position pixel and bitmap write operations. See glBitmap,
glDrawPixels, and glCopyPixels.
The current raster position consists of three window coordinates (x, y, z),
a clip coordinate w value, an eye coordinate distance, a valid bit, and
associated color data and texture coordinates. The w coordinate is a clip
coordinate, because w is not projected to window coordinates. glRasterPos4
specifies object coordinates x, y, z, and w explicitly. glRasterPos3
specifies object coordinate x, y, and z explicitly, while w is implicitly
set to one. glRasterPos2 uses the argument values for x and y while
implicitly setting z and w to zero and one.
The object coordinates presented by glRasterPos are treated just like those
of a glVertex command: They are transformed by the current modelview and
projection matrices and passed to the clipping stage. If the vertex is not
culled, then it is projected and scaled to window coordinates, which become
the new current raster position, and the GL_CURRENT_RASTER_POSITION_VALID
flag is set. If the vertex is culled, then the valid bit is cleared and
the current raster position and associated color and texture coordinates
are undefined.
The current raster position also includes some associated color data and
texture coordinates. If lighting is enabled, then GL_CURRENT_RASTER_COLOR,
in RGBA mode, or the GL_CURRENT_RASTER_INDEX, in color index mode, is set
to the color produced by the lighting calculation (see glLight,
glLightModel, and glShadeModel). If lighting is disabled, current color
(in RGBA mode, state variable GL_CURRENT_COLOR) or color index (in color
index mode, state variable GL_CURRENT_INDEX) is used to update the current
raster color.
Likewise, GL_CURRENT_RASTER_TEXTURE_COORDS is updated as a function of
GL_CURRENT_TEXTURE_COORDS, based on the texture matrix and the texture
generation functions (see glTexGen). Finally, the distance from the origin
of the eye coordinate system to the vertex as transformed by only the
modelview matrix replaces GL_CURRENT_RASTER_DISTANCE.
Initially, the current raster position is (0,0,0,1), the current raster
distance is 0, the valid bit is set, the associated RGBA color is
(1,1,1,1), the associated color index is 1, and the associated texture
coordinates are (0, 0, 0, 1). In RGBA mode, GL_CURRENT_RASTER_INDEX is
always 1; in color index mode, the current raster RGBA color always
maintains its initial value.
Notes
The raster position is modified both by glRasterPos and by glBitmap.
When the raster position coordinates are invalid, drawing commands that are
based on the raster position are ignored (that is, they do not result in
changes to GL state).
Errors
GL_INVALID_OPERATION is generated if glRasterPos is called between a call
to glBegin and the corresponding call to glEnd.
Associated Gets
glGet with argument GL_CURRENT_RASTER_POSITION
glGet with argument GL_CURRENT_RASTER_POSITION_VALID
glGet with argument GL_CURRENT_RASTER_DISTANCE
glGet with argument GL_CURRENT_RASTER_COLOR
glGet with argument GL_CURRENT_RASTER_INDEX
glGet with argument GL_CURRENT_RASTER_TEXTURE_COORDS
See Also
glBitmap, glCopyPixels, glDrawPixels, glLight, glLightModel, glShadeModel,
glTexCoord, glTexGen, glVertex
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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.95. glReadBuffer ΓòÉΓòÉΓòÉ
OpenGL man pages
glReadBuffer
Name
glReadBuffer - select a color buffer source for pixels
C Specification
void glReadBuffer( GLenum mode )
Parameters
mode Specifies a color buffer. Accepted values are GL_FRONT_LEFT,
GL_FRONT_RIGHT, GL_BACK_LEFT, GL_BACK_RIGHT, GL_FRONT, GL_BACK,
GL_LEFT, GL_RIGHT, and GL_AUXi, where i is between 0 and
GL_AUX_BUFFERS -1.
Description
glReadBuffer specifies a color buffer as the source for subsequent
glReadPixels and glCopyPixels commands. mode accepts one of twelve or more
predefined values. (GL_AUX0 through GL_AUX3 are always defined.) In a
fully configured system, GL_FRONT, GL_LEFT, and GL_FRONT_LEFT all name the
front left buffer, GL_FRONT_RIGHT and GL_RIGHT name the front right buffer,
and GL_BACK_LEFT and GL_BACK name the back left buffer.
Nonstereo double-buffered configurations have only a front left and a back
left buffer. Single-buffered configurations have a front left and a front
right buffer if stereo, and only a front left buffer if nonstereo. It is
an error to specify a nonexistent buffer to glReadBuffer.
By default, mode is GL_FRONT in single-buffered configurations, and GL_BACK
in double-buffered configurations.
Errors
GL_INVALID_ENUM is generated if mode is not one of the twelve (or more)
accepted values.
GL_INVALID_OPERATION is generated if mode specifies a buffer that does not
exist.
GL_INVALID_OPERATION is generated if glReadBuffer is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_READ_BUFFER
See Also
glCopyPixels, glDrawBuffer, glReadPixels
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ΓòÉΓòÉΓòÉ 3.96. glReadPixels ΓòÉΓòÉΓòÉ
OpenGL man pages
glReadPixels
Name
glReadPixels - read a block of pixels from the frame buffer
C Specification
void glReadPixels( GLint x,
GLint y,
GLsizei width,
GLsizei height,
GLenum format,
GLenum type,
GLvoid *pixels )
Parameters
x, y Specify the window coordinates of the first pixel that is read from
the frame buffer. This location is the lower left corner of a
rectangular block of pixels.
width, height
Specify the dimensions of the pixel rectangle. width and height of
one correspond to a single pixel.
format
Specifies the format of the pixel data. The following symbolic values
are accepted: GL_COLOR_INDEX, GL_STENCIL_INDEX, GL_DEPTH_COMPONENT,
GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA, GL_LUMINANCE,
and GL_LUMINANCE_ALPHA.
type Specifies the data type of the pixel data. Must be one of
GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT, GL_SHORT,
GL_UNSIGNED_INT, GL_INT, or GL_FLOAT.
pixels
Returns the pixel data.
Description
glReadPixels returns pixel data from the frame buffer, starting with the
pixel whose lower left corner is at location (x, y), into client memory
starting at location pixels. Several parameters control the processing of
the pixel data before it is placed into client memory. These parameters
are set with three commands: glPixelStore, glPixelTransfer, and glPixelMap.
This reference page describes the effects on glReadPixels of most, but not
all of the parameters specified by these three commands.
glReadPixels returns values from each pixel with lower left-hand corner at
(x + i, y + j) for 0<=i<width and 0<=j<height. This pixel is said to be the
ith pixel in the jth row. Pixels are returned in row order from the lowest
to the highest row, left to right in each row.
format specifies the format for the returned pixel values. Accepted values
for format are as follows:
GL_COLOR_INDEX
Color indices are read from the color buffer selected by
glReadBuffer. Each index is converted to fixed point, shifted
left or right depending on the value and sign of GL_INDEX_SHIFT,
and added to GL_INDEX_OFFSET. If GL_MAP_COLOR is GL_TRUE, indices
are replaced by their mappings in the table GL_PIXEL_MAP_I_TO_I.
GL_STENCIL_INDEX
Stencil values are read from the stencil buffer. Each index is
converted to fixed point, shifted left or right depending on the
value and sign of GL_INDEX_SHIFT, and added to GL_INDEX_OFFSET.
If GL_MAP_STENCIL is GL_TRUE, indices are replaced by their
mappings in the table GL_PIXEL_MAP_S_TO_S.
GL_DEPTH_COMPONENT
Depth values are read from the depth buffer. Each component is
converted to floating point such that the minimum depth value
maps to 0.0 and the maximum value maps to 1.0. Each component is
then multiplied by GL_DEPTH_SCALE, added to GL_DEPTH_BIAS, and
finally clamped to the range [0,1].
GL_RED
GL_GREEN
GL_BLUE
GL_ALPHA
GL_RGB
GL_RGBA
GL_LUMINANCE
GL_LUMINANCE_ALPHA
Processing differs depending on whether color buffers store color
indices or RGBA color components. If color indices are stored,
they are read from the color buffer selected by glReadBuffer.
Each index is converted to fixed point, shifted left or right
depending on the value and sign of GL_INDEX_SHIFT, and added to
GL_INDEX_OFFSET. Indices are then replaced by the red, green,
blue, and alpha values obtained by indexing the
GL_PIXEL_MAP_I_TO_R, GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B,
and GL_PIXEL_MAP_I_TO_A tables. Each of these tables must be of
n
size 2 , but n may be different for different tables. Before an
n
index is used to look up a value in a table of size 2 it must
n
be masked against 2 -1.
If RGBA color components are stored in the color buffers, they
are read from the color buffer selected by glReadBuffer. Each
color component is converted to floating point such that zero
intensity maps to 0.0 and full intensity maps to 1.0. Each
component is then multiplied by GL_c_SCALE and added to
GL_c_BIAS, where c is RED, GREEN, BLUE, or ALPHA. Finally, if
GL_MAP_COLOR is GL_TRUE, Each component is clamped to the range
[0,1], scaled to the size of its corresponding table, and is then
replaced by its mapping in the table GL_PIXEL_MAP_c_TO_c, where c
is R, G, B, or A.
Unneeded data is then discarded. For example, GL_RED discards
the green, blue, and alpha components, while GL_RGB discards only
the alpha component. GL_LUMINANCE computes a single component
value as the sum of the red, green, and blue components, and
GL_LUMINANCE_ALPHA does the same, while keeping alpha as a second
value. The final values are clamped to the range [0,1].
The shift, scale, bias, and lookup factors described above are all
specified by glPixelTransfer. The lookup table contents themselves are
specified by glPixelMap.
The final step involves converting the indices or components to the proper
format, as specified by type. If format is GL_COLOR_INDEX or
GL_STENCIL_INDEX and type is not GL_FLOAT, each index is masked with the
mask value given in the following table. If type is GL_FLOAT, then each
integer index is converted to single-precision floating-point format.
If format is GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_RGBA,
GL_LUMINANCE, or GL_LUMINANCE_ALPHA and type is not GL_FLOAT, each
component is multiplied by the multiplier shown in the following table. If
type is GL_FLOAT, then each component is passed as is (or converted to the
client's single-precision floating-point format if it is different from the
one used by the GL).
-------------------------------------------------------
| type | index mask | component conversion |
-------------------------------------------------------
|GL_UNSIGNED_BYTE | 2^8-1 | (2^8-1)c |
| GL_BYTE | 2^7-1 | [(2^8-1)c-1]/2 |
| GL_BITMAP | 1 | 1 |
|GL_UNSIGNED_SHORT | 2^16-1 | (2^16-1)c |
| GL_SHORT | 2^15-1 | [(2^16-1)c-1]/2 |
| GL_UNSIGNED_INT | 2^32-1 | (2^32-1)c |
| GL_INT | 2^31-1 | [(2^32-1)c-1]/2 |
| GL_FLOAT | none | c |
-------------------------------------------------------
Return values are placed in memory as follows. If format is
GL_COLOR_INDEX, GL_STENCIL_INDEX, GL_DEPTH_COMPONENT, GL_RED, GL_GREEN,
GL_BLUE, GL_ALPHA, or GL_LUMINANCE, a single value is returned and the data
for the ith pixel in the jth row is placed in location (j) width + i.
GL_RGB returns three values, GL_RGBA returns four values, and
GL_LUMINANCE_ALPHA returns two values for each pixel, with all values
corresponding to a single pixel occupying contiguous space in pixels.
Storage parameters set by glPixelStore, such as GL_PACK_SWAP_BYTES and
GL_PACK_LSB_FIRST, affect the way that data is written into memory. See
glPixelStore for a description.
Notes
Values for pixels that lie outside the window connected to the current GL
context are undefined.
If an error is generated, no change is made to the contents of pixels.
Errors
GL_INVALID_ENUM is generated if format or type is not an accepted value.
GL_INVALID_VALUE is generated if either width or height is negative.
GL_INVALID_OPERATION is generated if format is GL_COLOR_INDEX and the color
buffers store RGBA color components.
GL_INVALID_OPERATION is generated if format is GL_STENCIL_INDEX and there
is no stencil buffer.
GL_INVALID_OPERATION is generated if format is GL_DEPTH_COMPONENT and there
is no depth buffer.
GL_INVALID_OPERATION is generated if glReadPixels is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_INDEX_MODE
See Also
glCopyPixels, glDrawPixels, glPixelMap, glPixelStore, glPixelTransfer,
glReadBuffer
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ΓòÉΓòÉΓòÉ 3.97. glRect ΓòÉΓòÉΓòÉ
OpenGL man pages
glRect
Name
glRectd, glRectf, glRecti, glRects, glRectdv,
glRectfv, glRectiv, glRectsv
- draw a rectangle
C Specification
void glRectd( GLdouble x1,
GLdouble y1,
GLdouble x2,
GLdouble y2 )
void glRectf( GLfloat x1,
GLfloat y1,
GLfloat x2,
GLfloat y2 )
void glRecti( GLint x1,
GLint y1,
GLint x2,
GLint y2 )
void glRects( GLshort x1,
GLshort y1,
GLshort x2,
GLshort y2 )
Parameters
x1, y1 Specify one vertex of a rectangle.
x2, y2 Specify the opposite vertex of the rectangle.
C Specification
void glRectdv( const GLdouble *v1,
const GLdouble *v2 )
void glRectfv( const GLfloat *v1,
const GLfloat *v2 )
void glRectiv( const GLint *v1,
const GLint *v2 )
void glRectsv( const GLshort *v1,
const GLshort *v2 )
Parameters
v1 Specifies a pointer to one vertex of a rectangle.
v2 Specifies a pointer to the opposite vertex of the rectangle.
Description
glRect supports efficient specification of rectangles as two corner points.
Each rectangle command takes four arguments, organized either as two
consecutive pairs of (x,y) coordinates, or as two pointers to arrays, each
containing an (x,y) pair. The resulting rectangle is defined in the z=0
plane.
glRect(x1, y1, x2, y2) is exactly equivalent to the following sequence:
glBegin(GL_POLYGON); glVertex2(x1, y1); glVertex2(x2, y1); glVertex2(x2,
y2); glVertex2(x1, y2); glEnd(); Note that if the second vertex is above
and to the right of the first vertex, the rectangle is constructed with a
counterclockwise winding.
Errors
GL_INVALID_OPERATION is generated if glRect is called between a call to
glBegin and the corresponding call to glEnd.
See Also
glBegin, glVertex
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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.98. glRenderMode ΓòÉΓòÉΓòÉ
OpenGL man pages
glRenderMode
Name
glRenderMode - set rasterization mode
C Specification
GLint glRenderMode( GLenum mode )
Parameters
mode Specifies the rasterization mode. Three values are accepted:
GL_RENDER, GL_SELECT, and GL_FEEDBACK. The default value is
GL_RENDER.
Description
glRenderMode sets the rasterization mode. It takes one argument, mode,
which can assume one of three predefined values:
GL_RENDER Render mode. Primitives are rasterized, producing pixel
fragments, which are written into the frame buffer. This
is the normal mode and also the default mode.
GL_SELECT Selection mode. No pixel fragments are produced, and no
change to the frame buffer contents is made. Instead, a
record of the names of primitives that would have been
drawn if the render mode was GL_RENDER is returned in a
select buffer, which must be created (see glSelectBuffer)
before selection mode is entered.
GL_FEEDBACK Feedback mode. No pixel fragments are produced, and no
change to the frame buffer contents is made. Instead, the
coordinates and attributes of vertices that would have been
drawn had the render mode been GL_RENDER is returned in a
feedback buffer, which must be created (see
glFeedbackBuffer) before feedback mode is entered.
The return value of glRenderMode is determined by the render mode at the
time glRenderMode is called, rather than by mode. The values returned for
the three render modes are as follows:
GL_RENDER Zero.
GL_SELECT The number of hit records transferred to the select buffer.
GL_FEEDBACK The number of values (not vertices) transferred to the
feedback buffer.
Refer to the glSelectBuffer and glFeedbackBuffer reference pages for more
details concerning selection and feedback operation.
Notes
If an error is generated, glRenderMode returns zero regardless of the
current render mode.
Errors
GL_INVALID_ENUM is generated if mode is not one of the three accepted
values.
GL_INVALID_OPERATION is generated if glSelectBuffer is called while the
render mode is GL_SELECT, or if glRenderMode is called with argument
GL_SELECT before glSelectBuffer is called at least once.
GL_INVALID_OPERATION is generated if glFeedbackBuffer is called while the
render mode is GL_FEEDBACK, or if glRenderMode is called with argument
GL_FEEDBACK before glFeedbackBuffer is called at least once.
GL_INVALID_OPERATION is generated if glRenderMode is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_RENDER_MODE
See Also
glFeedbackBuffer, glInitNames, glLoadName, glPassThrough, glPushName,
glSelectBuffer
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ΓòÉΓòÉΓòÉ 3.99. glRotate ΓòÉΓòÉΓòÉ
OpenGL man pages
glRotate
Name
glRotated, glRotatef - multiply the current matrix by a rotation matrix
C Specification
void glRotated( GLdouble angle,
GLdouble x,
GLdouble y,
GLdouble z )
void glRotatef( GLfloat angle,
GLfloat x,
GLfloat y,
GLfloat z )
Parameters
angle Specifies the angle of rotation, in degrees.
x, y, z
Specify the x, y, and z coordinates of a vector, respectively.
Description
glRotate computes a matrix that performs a counterclockwise rotation of
angle degrees about the vector from the origin through the point (x, y, z).
The current matrix (see glMatrixMode) is multiplied by this rotation
matrix, with the product replacing the current matrix. That is, if M is
the current matrix and R is the translation matrix, then M is replaced with
M Γòû R.
If the matrix mode is either GL_MODELVIEW or GL_PROJECTION, all objects
drawn after glRotate is called are rotated. Use glPushMatrix and
glPopMatrix to save and restore the unrotated coordinate system.
Errors
GL_INVALID_OPERATION is generated if glRotate is executed between
the execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glMatrixMode, glMultMatrix, glPushMatrix, glScale, glTranslate
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ΓòÉΓòÉΓòÉ 3.100. glScale ΓòÉΓòÉΓòÉ
OpenGL man pages
glScale
Name
glScaled, glScalef - multiply the current matrix by a general scaling
matrix
C Specification
void glScaled( GLdouble x,
GLdouble y,
GLdouble z )
void glScalef( GLfloat x,
GLfloat y,
GLfloat z )
Parameters
x, y, z
Specify scale factors along the x, y, and z axes, respectively.
Description
glScale produces a general scaling along the x, y, and z axes. The three
arguments indicate the desired scale factors along each of the three axes.
The resulting matrix is
| x 0 0 0 |
| |
| 0 y 0 0 |
| |
| 0 0 z 0 |
| |
| 0 0 0 1 |
The current matrix (see glMatrixMode) is multiplied by this scale matrix,
with the product replacing the current matrix. That is, if M is the
current matrix and S is the scale matrix, then M is replaced with M Γòû S.
If the matrix mode is either GL_MODELVIEW or GL_PROJECTION, all objects
drawn after glScale is called are scaled. Use glPushMatrix and glPopMatrix
to save and restore the unscaled coordinate system.
Notes
If scale factors other than 1.0 are applied to the modelview matrix and
lighting is enabled, automatic normalization of normals should probably
also be enabled (glEnable and glDisable with argument GL_NORMALIZE).
Errors
GL_INVALID_OPERATION is generated if glScale is executed between
the execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glMatrixMode, glMultMatrix, glPushMatrix, glRotate, glTranslate
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ΓòÉΓòÉΓòÉ 3.101. glScissor ΓòÉΓòÉΓòÉ
OpenGL man pages
glScissor
Name
glScissor - define the scissor box
C Specification
void glScissor( GLint x,
GLint y,
GLsizei width,
GLsizei height )
Parameters
x, y Specify the lower left corner of the scissor box. Initially (0,0).
width, height
Specify the width and height of the scissor box. When a GL context is
first attached to a window, width and height are set to the dimensions
of that window.
Description
The glScissor routine defines a rectangle, called the scissor box, in
window coordinates. The first two arguments, x and y, specify the lower
left corner of the box. width and height specify the width and height of
the box.
The scissor test is enabled and disabled using glEnable and glDisable with
argument GL_SCISSOR_TEST. While the scissor test is enabled, only pixels
that lie within the scissor box can be modified by drawing commands.
Window coordinates have integer values at the shared corners of frame
buffer pixels, so glScissor(0,0,1,1) allows only the lower left pixel in
the window to be modified, and glScissor(0,0,0,0) disallows modification
to all pixels in the window.
When the scissor test is disabled, it is as though the scissor box includes
the entire window.
Errors
GL_INVALID_VALUE is generated if either width or height is negative.
GL_INVALID_OPERATION is generated if glScissor is executed between
execution of glBegin and the corresponding execution ofglEnd.
Associated Gets
glGet with argument GL_SCISSOR_BOX
glIsEnabled with argument GL_SCISSOR_TEST
See Also
glEnable, glViewport
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ΓòÉΓòÉΓòÉ 3.102. glSelectBuffer ΓòÉΓòÉΓòÉ
OpenGL man pages
glSelectBuffer
Name
glSelectBuffer - establish a buffer for selection mode values
C Specification
void glSelectBuffer( GLsizei size,
GLuint *buffer )
Parameters
size Specifies the size of buffer.
buffer Returns the selection data.
Description
glSelectBuffer has two arguments: buffer is a pointer to an array of
unsigned integers, and size indicates the size of the array. buffer
returns values from the name stack (see glInitNames, glLoadName,
glPushName) when the rendering mode is GL_SELECT (see glRenderMode).
glSelectBuffer must be issued before selection mode is enabled, and it must
not be issued while the rendering mode is GL_SELECT.
Selection is used by a programmer to determine which primitives are drawn
into some region of a window. The region is defined by the current
modelview and perspective matrices.
In selection mode, no pixel fragments are produced from rasterization.
Instead, if a primitive intersects the clipping volume defined by the
viewing frustum and the user-defined clipping planes, this primitive causes
a selection hit. (With polygons, no hit occurs if the polygon is culled.)
When a change is made to the name stack, or when glRenderMode is called, a
hit record is copied to buffer if any hits have occurred since the last
such event (name stack change or glRenderMode call). The hit record
consists of the number of names in the name stack at the time of the event,
followed by the minimum and maximum depth values of all vertices that hit
since the previous event, followed by the name stack contents, bottom name
first.
Returned depth values are mapped such that the largest unsigned integer
value corresponds to window coordinate depth 1.0, and zero corresponds to
window coordinate depth 0.0.
An internal index into buffer is reset to zero whenever selection mode is
entered. Each time a hit record is copied into buffer, the index is
incremented to point to the cell just past the end of the block of names -
that is, to the next available cell. If the hit record is larger than the
number of remaining locations in buffer, as much data as can fit is copied,
and the overflow flag is set. If the name stack is empty when a hit record
is copied, that record consists of zero followed by the minimum and maximum
depth values.
Selection mode is exited by calling glRenderMode with an argument other
than GL_SELECT. Whenever glRenderMode is called while the render mode is
GL_SELECT, it returns the number of hit records copied to buffer, resets
the overflow flag and the selection buffer pointer, and initializes the
name stack to be empty. If the overflow bit was set when glRenderMode was
called, a negative hit record count is returned.
Notes
The contents of buffer are undefined until glRenderMode is called with an
argument other than GL_SELECT.
glBegin/glEnd primitives and calls to glRasterPos can result in hits.
Errors
GL_INVALID_VALUE is generated if size is negative.
GL_INVALID_OPERATION is generated if glSelectBuffer is called while the
render mode is GL_SELECT, or if glRenderMode is called with argument
GL_SELECT before glSelectBuffer is called at least once.
GL_INVALID_OPERATION is generated if glSelectBuffer is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_NAME_STACK_DEPTH
See Also
glFeedbackBuffer, glInitNames, glLoadName, glPushName, glRenderMode
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ΓòÉΓòÉΓòÉ 3.103. glShadeModel ΓòÉΓòÉΓòÉ
OpenGL man pages
glShadeModel
Name
glShadeModel - select flat or smooth shading
C Specification
void glShadeModel( GLenum mode )
Parameters
mode Specifies a symbolic value representing a shading technique.
Accepted values are GL_FLAT and GL_SMOOTH. The default is GL_SMOOTH.
Description
GL primitives can have either flat or smooth shading. Smooth shading, the
default, causes the computed colors of vertices to be interpolated as the
primitive is rasterized, typically assigning different colors to each
resulting pixel fragment. Flat shading selects the computed color of just
one vertex and assigns it to all the pixel fragments generated by
rasterizing a single primitive. In either case, the computed color of a
vertex is the result of lighting, if lighting is enabled, or it is the
current color at the time the vertex was specified, if lighting is
disabled.
Flat and smooth shading are indistinguishable for points. Counting
vertices and primitives from one starting when glBegin is issued, each
flat-shaded line segment i is given the computed color of vertex i+1, its
second vertex. Counting similarly from one, each flat-shaded polygon is
given the computed color of the vertex listed in the following table. This
is the last vertex to specify the polygon in all cases except single
polygons, where the first vertex specifies the flat-shaded color.
---------------------------------------
|primitive type of polygon | i |
---------------------------------------
|Single polygon (i=1) | 1 |
|Triangle strip | i+2 |
|Triangle fan | i+2 |
|Independent triangle | 3i |
|Quad strip | 2i+2 |
|Independent quad | 4i |
---------------------------------------
Flat and smooth shading are specified by glShadeModel with mode set to
GL_FLAT and GL_SMOOTH, respectively.
Errors
GL_INVALID_ENUM is generated if mode is any value other than GL_FLAT or
GL_SMOOTH.
GL_INVALID_OPERATION is generated if glShadeModel is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_SHADE_MODEL
See Also
glBegin, glColor, glLight, glLightModel
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ΓòÉΓòÉΓòÉ 3.104. glStencilFunc ΓòÉΓòÉΓòÉ
OpenGL man pages
glStencilFunc
Name
glStencilFunc - set function and reference value for stencil testing
C Specification
void glStencilFunc( GLenum func,
GLint ref,
GLuint mask )
Parameters
func Specifies the test function. Eight tokens are valid: GL_NEVER,
GL_LESS, GL_LEQUAL, GL_GREATER, GL_GEQUAL, GL_EQUAL, GL_NOTEQUAL, and
GL_ALWAYS.
ref Specifies the reference value for the stencil test. ref is clamped
n
to the range [0,2 -1], where n is the number of bitplanes in the
stencil buffer.
mask Specifies a mask that is ANDed with both the reference value and the
stored stencil value when the test is done.
Description
Stenciling, like z-buffering, enables and disables drawing on a per-pixel
basis. You draw into the stencil planes using GL drawing primitives, then
render geometry and images, using the stencil planes to mask out portions
of the screen. Stenciling is typically used in multipass rendering
algorithms to achieve special effects, such as decals, outlining, and
constructive solid geometry rendering.
The stencil test conditionally eliminates a pixel based on the outcome of a
comparison between the reference value and the value in the stencil buffer.
The test is enabled by glEnable and glDisable with argument
GL_STENCIL_TEST. Actions taken based on the outcome of the stencil test
are specified with glStencilOp.
func is a symbolic constant that determines the stencil comparison
function. It accepts one of eight values, shown below. ref is an integer
reference value that is used in the stencil comparison. It is clamped to
the range [0,2n-1], where n is the number of bitplanes in the stencil
buffer. mask is bitwise ANDed with both the reference value and the stored
stencil value, with the ANDed values participating in the comparison.
If stencil represents the value stored in the corresponding stencil buffer
location, the following list shows the effect of each comparison function
that can be specified by func. Only if the comparison succeeds is the
pixel passed through to the next stage in the rasterization process (see
glStencilOp). All tests treat stencil values as unsigned integers in the
range [0,2n-1], where n is the number of bitplanes in the stencil buffer.
Here are the values accepted by func:
GL_NEVER Always fails.
GL_LESS Passes if ( ref & mask ) < ( stencil & mask ).
GL_LEQUAL Passes if ( ref & mask ) <= ( stencil & mask ).
GL_GREATER Passes if ( ref & mask ) > ( stencil & mask ).
GL_GEQUAL Passes if ( ref & mask ) >= ( stencil & mask ).
GL_EQUAL Passes if ( ref & mask ) = ( stencil & mask ).
GL_NOTEQUAL Passes if ( ref & mask ) != ( stencil & mask ).
GL_ALWAYS Always passes.
Notes
Initially, the stencil test is disabled. If there is no stencil buffer, no
stencil modification can occur and it is as if the stencil test always
passes.
Errors
GL_INVALID_ENUM is generated if func is not one of the eight accepted
values.
GL_INVALID_OPERATION is generated if glStencilFunc is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_STENCIL_FUNC
glGet with argument GL_STENCIL_VALUE_MASK
glGet with argument GL_STENCIL_REF
glGet with argument GL_STENCIL_BITS
glIsEnabled with argument GL_STENCIL_TEST
See Also
glAlphaFunc, glBlendFunc, glDepthFunc, glEnable, glIsEnabled, glLogicOp,
glStencilOp
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ΓòÉΓòÉΓòÉ 3.105. glStencilMask ΓòÉΓòÉΓòÉ
OpenGL man pages
glStencilMask
Name
glStencilMask - control the writing of individual bits in the stencil
planes
C Specification
void glStencilMask( GLuint mask )
Parameters
mask Specifies a bit mask to enable and disable writing of individual bits
in the stencil planes. Initially, the mask is all ones.
Description
glStencilMask controls the writing of individual bits in the stencil
planes. The least significant n bits of mask, where n is the number of
bits in the stencil buffer, specify a mask. Wherever a one appears in the
mask, the corresponding bit in the stencil buffer is made writable. Where
a zero appears, the bit is write-protected. Initially, all bits are
enabled for writing.
Errors
GL_INVALID_OPERATION is generated if glStencilMask is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_STENCIL_WRITEMASK
glGet with argument GL_STENCIL_BITS
See Also
glColorMask, glDepthMask, glIndexMask, glStencilFunc, glStencilOp
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ΓòÉΓòÉΓòÉ 3.106. glStencilOp ΓòÉΓòÉΓòÉ
OpenGL man pages
glStencilOp
Name
glStencilOp - set stencil test actions
C Specification
void glStencilOp( GLenum fail,
GLenum zfail,
GLenum zpass )
Parameters
fail Specifies the action to take when the stencil test fails. Six
symbolic constants are accepted: GL_KEEP, GL_ZERO, GL_REPLACE,
GL_INCR, GL_DECR, and GL_INVERT.
zfail Specifies stencil action when the stencil test passes, but the depth
test fails. zfail accepts the same symbolic constants as fail.
zpass Specifies stencil action when both the stencil test and the depth
test pass, or when the stencil test passes and either there is no
depth buffer or depth testing is not enabled. zpass accepts the
same symbolic constants as fail.
Description
Stenciling, like z-buffering, enables and disables drawing on a per-pixel
basis. You draw into the stencil planes using GL drawing primitives, then
render geometry and images, using the stencil planes to mask out portions
of the screen. Stenciling is typically used in multipass rendering
algorithms to achieve special effects, such as decals, outlining, and
constructive solid geometry rendering.
The stencil test conditionally eliminates a pixel based on the outcome of a
comparison between the value in the stencil buffer and a reference value.
The test is enabled with glEnable and glDisable calls with argument
GL_STENCIL_TEST, and controlled with glStencilFunc.
glStencilOp takes three arguments that indicate what happens to the stored
stencil value while stenciling is enabled. If the stencil test fails, no
change is made to the pixel's color or depth buffers, and fail specifies
what happens to the stencil buffer contents. The six possible actions are
as follows:
GL_KEEP Keeps the current value.
GL_ZERO Sets the stencil buffer value to zero.
GL_REPLACE Sets the stencil buffer value to ref, as specified by
glStencilFunc.
GL_INCR Increments the current stencil buffer value. Clamps to the
maximum representable unsigned value.
GL_DECR Decrements the current stencil buffer value. Clamps to
zero.
GL_INVERT Bitwise inverts the current stencil buffer value.
Stencil buffer values are treated as unsigned integers. When incremented
and decremented, values are clamped to 0 and 2n-1, where n is the value
returned by querying GL_STENCIL_BITS.
The other two arguments to glStencilOp specify stencil buffer actions
should subsequent depth buffer tests succeed (zpass) or fail (zfail). (See
glDepthFunc.) They are specified using the same six symbolic constants as
fail. Note that zfail is ignored when there is no depth buffer, or when
the depth buffer is not enabled. In these cases, fail and zpass specify
stencil action when the stencil test fails and passes, respectively.
Notes
Initially the stencil test is disabled. If there is no stencil buffer, no
stencil modification can occur and it is as if the stencil tests always
pass, regardless of any call to glStencilOp.
Errors
GL_INVALID_ENUM is generated if fail, zfail, or zpass is any value other
than the six defined constant values.
GL_INVALID_OPERATION is generated if glStencilOp is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_STENCIL_FAIL
glGet with argument GL_STENCIL_PASS_DEPTH_PASS
glGet with argument GL_STENCIL_PASS_DEPTH_FAIL
glGet with argument GL_STENCIL_BITS
glIsEnabled with argument GL_STENCIL_TEST
See Also
glAlphaFunc, glBlendFunc, glDepthFunc, glEnable, glLogicOp, glStencilFunc
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ΓòÉΓòÉΓòÉ 3.107. glTexCoord ΓòÉΓòÉΓòÉ
OpenGL man pages
glTexCoord
Name
glTexCoord1d, glTexCoord1f, glTexCoord1i, glTexCoord1s, glTexCoord2d,
glTexCoord2f, glTexCoord2i, glTexCoord2s, glTexCoord3d, glTexCoord3f,
glTexCoord3i, glTexCoord3s, glTexCoord4d, glTexCoord4f, glTexCoord4i,
glTexCoord4s, glTexCoord1dv, glTexCoord1fv, glTexCoord1iv, glTexCoord1sv,
glTexCoord2dv, glTexCoord2fv, glTexCoord2iv, glTexCoord2sv, glTexCoord3dv,
glTexCoord3fv, glTexCoord3iv, glTexCoord3sv, glTexCoord4dv, glTexCoord4fv,
glTexCoord4iv, glTexCoord4sv - set the current texture coordinates
C Specification
void glTexCoord1d( GLdouble s )
void glTexCoord1f( GLfloat s )
void glTexCoord1i( GLint s )
void glTexCoord1s( GLshort s )
void glTexCoord2d( GLdouble s,
GLdouble t )
void glTexCoord2f( GLfloat s,
GLfloat t )
void glTexCoord2i( GLint s,
GLint t )
void glTexCoord2s( GLshort s,
GLshort t )
void glTexCoord3d( GLdouble s,
GLdouble t,
GLdouble r )
void glTexCoord3f( GLfloat s,
GLfloat t,
GLfloat r )
void glTexCoord3i( GLint s,
GLint t,
GLint r )
void glTexCoord3s( GLshort s,
GLshort t,
GLshort r )
void glTexCoord4d( GLdouble s,
GLdouble t,
GLdouble r,
GLdouble q )
void glTexCoord4f( GLfloat s,
GLfloat t,
GLfloat r,
GLfloat q )
void glTexCoord4i( GLint s,
GLint t,
GLint r,
GLint q )
void glTexCoord4s( GLshort s,
GLshort t,
GLshort r,
GLshort q )
Parameters
s, t, r, q
Specify s, t, r, and q texture coordinates. Not all parameters
are present in all forms of the command.
C Specification
void glTexCoord1dv( const GLdouble *v )
void glTexCoord1fv( const GLfloat *v )
void glTexCoord1iv( const GLint *v )
void glTexCoord1sv( const GLshort *v )
void glTexCoord2dv( const GLdouble *v )
void glTexCoord2fv( const GLfloat *v )
void glTexCoord2iv( const GLint *v )
void glTexCoord2sv( const GLshort *v )
void glTexCoord3dv( const GLdouble *v )
void glTexCoord3fv( const GLfloat *v )
void glTexCoord3iv( const GLint *v )
void glTexCoord3sv( const GLshort *v )
void glTexCoord4dv( const GLdouble *v )
void glTexCoord4fv( const GLfloat *v )
void glTexCoord4iv( const GLint *v )
void glTexCoord4sv( const GLshort *v )
Parameters
v Specifies a pointer to an array of one, two, three, or four elements,
which in turn specify the s, t, r, and q texture coordinates.
Description
The current texture coordinates are part of the data that is associated
with each vertex and with the current raster position. They are set with
glTexCoord.
glTexCoord specifies texture coordinates in one, two, three, or four
dimensions. glTexCoord1 sets the current texture coordinates to (s, 0, 0,
1); a call to glTexCoord2 sets them to (s, t, 0, 1). Similarly,
glTexCoord3 specifies the texture coordinates as (s, t, r, 1), and
glTexCoord4 defines all four components explicitly as (s, t, r, q).
Notes
The current texture coordinates can be updated at any time. In particular,
glTexCoord can be called between a call to glBegin and the corresponding
call to glEnd.
Associated Gets
glGet with argument GL_CURRENT_TEXTURE_COORDS
See Also
glVertex
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Introduction | Alphabetic | Specification
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ΓòÉΓòÉΓòÉ 3.108. glTexCoordPointerEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glTexCoordPointerEXT
Name
glTexCoordPointerEXT - define an array of texture coordinates
C Specification
void glTexCoordPointerEXT( GLint size,
GLenum type,
GLsizei stride,
GLsizei count,
const GLvoid *pointer )
Parameters
size Specifies the number of coordinates per array element. It must be
1, 2, 3 or 4.
type Specifies the data type of each texture coordinate. Symbolic
constants GL_SHORT, GL_INT, GL_FLOAT, or GL_DOUBLE_EXT, are
accepted.
stride Specifies the byte offset between consecutive array elements. If
stride is zero the array elements are understood to be tightly
packed.
count Specifies the number of array elements, counting from the first,
that are static.
pointer Specifies a pointer to the first coordinate of the first element
in the array.
Description
glTexCoordPointerEXT specifies the location and data format of an array of
texture coordinates to use when rendering using the vertex array extension.
size specifies the number of coordinates per element, and must be 1, 2, 3,
or 4. type specifies the data type of each texture coordinate and stride
gives the byte stride from one array element to the next allowing vertexes
and attributes to be packed into a single array or stored in separate arrays.
(Single-array storage may be more efficient on some implementations.) count
indicates the number of array elements (counting from the first) that are
static. Static elements may be modified by the application, but once they
are modified, the application must explicitly respecify the array before
using it for any rendering. When a texture coordinate array is specified,
size, type, stride, count, and pointer are saved as client-side state, and
static array elements may be cached by the implementation.
The texture coordinate array is enabled and disabled using glEnable and
glDisable with the argument GL_TEXTURE_COORD_ARRAY_EXT. If enabled, the
texture coordinate array is used when glDrawArraysEXT or glArrayElementEXT
is called.
Use glDrawArraysEXT to define a sequence of primitives (all of the same
type) from pre-specified vertex and vertex attribute arrays. Use
glArrayElementEXT to specify primitives by indexing vertexes and vertex
attributes.
Notes
Non-static array elements are not accessed until glArrayElementEXT or
glDrawArraysEXT is executed.
By default the texture coordinate array is disabled and it won't be
accessed when glArrayElementEXT or glDrawArraysEXT is called.
Although it is not an error to call glTexCoordPointerEXT between the
execution of glBegin and the corresponding execution of glEnd, the results
are undefined.
glTexCoordPointerEXT will typically be implemented on the client side with
no protocol.
Since the texture coordinate array parameters are client side state, they
are not saved or restored by glPushAttrib and glPopAttrib.
glTexCoordPointerEXT commands are not entered into display lists.
glTexCoordPointerEXT is part of the EXT_vertex_array extension,
not part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
Errors
GL_INVALID_VALUE is generated if size is not 1, 2, 3, or 4.
GL_INVALID_ENUM is generated if type is not an accepted value.
GL_INVALID_VALUE is generated if stride or count is negative
Associated Gets
glIsEnabled with argument GL_TEXTURE_COORD_ARRAY_EXT
glGet with argument GL_TEXTURE_COORD_ARRAY_SIZE_EXT
glGet with argument GL_TEXTURE_COORD_ARRAY_TYPE_EXT
glGet with argument GL_TEXTURE_COORD_ARRAY_STRIDE_EXT
glGet with argument GL_TEXTURE_COORD_ARRAY_COUNT_EXT
glGetPointervEXT with argument GL_TEXTURE_COORD_ARRAY_POINTER_EXT
See Also
glArrayElementEXT, glColorPointerEXT, glDrawArraysEXT,
glEdgeFlagPointerEXT, glGetPointervEXT, glIndexPointerEXT,
glNormalPointerEXT, glVertexPointerEXT, glEnable
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ΓòÉΓòÉΓòÉ 3.109. glTexEnv ΓòÉΓòÉΓòÉ
OpenGL man pages
glTexEnv
Name
glTexEnvf, glTexEnvi, glTexEnvfv, glTexEnviv - set texture environment
parameters
C Specification
void glTexEnvf( GLenum target,
GLenum pname,
GLfloat param )
void glTexEnvi( GLenum target,
GLenum pname,
GLint param )
Parameters
target Specifies a texture environment. Must be GL_TEXTURE_ENV.
pname Specifies the symbolic name of a single-valued texture environment
parameter. Must be GL_TEXTURE_ENV_MODE.
param Specifies a single symbolic constant, one of GL_MODULATE, GL_DECAL,
or GL_BLEND.
C Specification
void glTexEnvfv( GLenum target,
GLenum pname,
const GLfloat *params )
void glTexEnviv( GLenum target,
GLenum pname,
const GLint *params )
Parameters
target
Specifies a texture environment. Must be GL_TEXTURE_ENV.
pname
Specifies the symbolic name of a texture environment parameter.
Accepted values are GL_TEXTURE_ENV_MODE and GL_TEXTURE_ENV_COLOR.
params
Specifies a pointer to an array of parameters: either a single
symbolic constant or an RGBA color.
Description
A texture environment specifies how texture values are interpreted when a
fragment is textured. target must be GL_TEXTURE_ENV. pname can be either
GL_TEXTURE_ENV_MODE or GL_TEXTURE_ENV_COLOR.
If pname is GL_TEXTURE_ENV_MODE, then params is (or points to) the symbolic
name of a texture function. Three texture functions are defined:
GL_MODULATE, GL_DECAL, and GL_BLEND
A texture function acts on the fragment to be textured using the texture
image value that applies to the fragment (see glTexParameter) and produces
an RGBA color for that fragment. The following table shows how the RGBA
color is produced for each of the three texture functions that can be
chosen. C is a triple of color values (RGB) and A is the associated alpha
value. RGBA values extracted from a texture image are in the range [0,1].
The subscript f refers to the incoming fragment, the subscript t to the
texture image, the subscript c to the texture environment color, and
subscript v indicates a value produced by the texture function.
A texture image can have up to four components per texture element (see
glTexImage1D and glTexImage2D). In a one-component image, L indicates
t
that single component. A two-component image uses L and A . A three-
t t
component image has only a color value, C . A four-component image has
t
both a color value C and an alpha value A .
t t
----------------------------------------------------------------
| number of || texture functions |
|components || GL_MODULATE GL_DECAL GL_BLEND |
----------------------------------------------------------------
| || C =L C | | C =(1-L )C +L C |
| 1 || v t f | undefined | v t f t c |
| || A =A | | A =A |
| || v f | | v f |
|-----------||------------|------------------|------------------|
| || C =L C | | C =(1-L )C +L C |
| 2 || v t f | undefined | v t f t c |
| || A =A A | | A =A A |
| || v t f | | v t f |
|-----------||------------|------------------|------------------|
| || C =C C | C =C | |
| 3 || v t f | v t | undefined |
| || A =A | A =A | |
| || v f | v f | |
|-----------||------------|------------------|------------------|
| || C =C C | C =(1-A )C +A C | |
| 4 || v t f | v t f t t | undefined |
| || A =A A | A =A | |
| || v t f | v f | |
----------------------------------------------------------------
If pname is GL_TEXTURE_ENV_COLOR, params is a pointer to an array that
holds an RGBA color consisting of four values. Integer color components
are interpreted linearly such that the most positive integer maps to 1.0,
and the most negative integer maps to -1.0. The values are clamped to the
range [0,1] when they are specified. C takes these four values.
c
GL_TEXTURE_ENV_MODE defaults to GL_MODULATE and GL_TEXTURE_ENV_COLOR
defaults to (0,0,0,0).
Errors
GL_INVALID_ENUM is generated when target or pname is not one of the
accepted defined values, or when params should have a defined constant
value (based on the value of pname) and does not.
GL_INVALID_OPERATION is generated if glTexEnv is executed between
the execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetTexEnv
See Also
glTexImage1D, glTexImage2D, glTexParameter
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ΓòÉΓòÉΓòÉ 3.110. glTexGen ΓòÉΓòÉΓòÉ
OpenGL man pages
glTexGen
Name
glTexGend, glTexGenf, glTexGeni, glTexGendv, glTexGenfv,
glTexGeniv -
control the generation of texture coordinates
C Specification
void glTexGend( GLenum coord,
GLenum pname,
GLdouble param )
void glTexGenf( GLenum coord,
GLenum pname,
GLfloat param )
void glTexGeni( GLenum coord,
GLenum pname,
GLint param )
Parameters
coord Specifies a texture coordinate. Must be one of the following:
GL_S, GL_T, GL_R, or GL_Q.
pname Specifies the symbolic name of the texture-coordinate generation
function. Must be GL_TEXTURE_GEN_MODE.
param Specifies a single-valued texture generation parameter, one of
GL_OBJECT_LINEAR, GL_EYE_LINEAR, or GL_SPHERE_MAP.
C Specification
void glTexGendv( GLenum coord,
GLenum pname,
const GLdouble *params )
void glTexGenfv( GLenum coord,
GLenum pname,
const GLfloat *params )
void glTexGeniv( GLenum coord,
GLenum pname,
const GLint *params )
Parameters
coord
Specifies a texture coordinate. Must be one of the following: GL_S,
GL_T, GL_R, or GL_Q.
pname
Specifies the symbolic name of the texture-coordinate generation
function or function parameters. Must be GL_TEXTURE_GEN_MODE,
GL_OBJECT_PLANE, or GL_EYE_PLANE.
params
Specifies a pointer to an array of texture generation parameters. If
pname is GL_TEXTURE_GEN_MODE, then the array must contain a single
symbolic constant, one of GL_OBJECT_LINEAR, GL_EYE_LINEAR, or
GL_SPHERE_MAP. Otherwise, params holds the coefficients for the
texture-coordinate generation function specified by pname.
Description
glTexGen selects a texture-coordinate generation function or supplies
coefficients for one of the functions. coord names one of the (s,t,r,q)
texture coordinates, and it must be one of these symbols: GL_S, GL_T, GL_R,
or GL_Q. pname must be one of three symbolic constants:
GL_TEXTURE_GEN_MODE, GL_OBJECT_PLANE, or GL_EYE_PLANE. If pname is
GL_TEXTURE_GEN_MODE, then params chooses a mode, one of GL_OBJECT_LINEAR,
GL_EYE_LINEAR, or GL_SPHERE_MAP. If pname is either GL_OBJECT_PLANE or
GL_EYE_PLANE, params contains coefficients for the corresponding texture
generation function.
If the texture generation function is GL_OBJECT_LINEAR, the function
g=p x +p y +p z +p w
1 o 2 o 3 o 4 o
is used, where g is the value computed for the coordinate named in coord,
p , p , p , and p are the four values supplied in params, and x , y , z ,
1 2 3 4 o o o
and w are the object coordinates of the vertex. This function can be used
o
to texture-map terrain using sea level as a reference plane (defined by p ,
1
p , p , and p ). The altitude of a terrain vertex is computed by the
2 3 4
GL_OBJECT_LINEAR coordinate generation function as its distance from sea
level; that altitude is used to index the texture image to map white snow
onto peaks and green grass onto foothills, for example.
If the texture generation function is GL_EYE_LINEAR, the function
g=p'x' + p'y + p'z + p'w
1 e 2 e 3 e 4 e
is used, where
-1
(p' p' p' p') = (p p p p )ΓòûM
1 2 3 4 1 2 3 4
and x , y , z , and w are the eye coordinates of the vertex, p , p , p ,
e e e e 1 2 3
and p are the values supplied in params, and M is the modelview matrix
4
when glTexGen is invoked. If M is poorly conditioned or singular, texture
coordinates generated by the resulting function may be inaccurate or
undefined.
Note that the values in params define a reference plane in eye coordinates.
The modelview matrix that is applied to them may not be the same one in
effect when the polygon vertices are transformed. This function establishes
a field of texture coordinates that can produce dynamic contour lines on
moving objects.
If pname is GL_SPHERE_MAP and coord is either GL_S or GL_T, s and t
texture coordinates are generated as follows. Let u be the unit vector
pointing from the origin to the polygon vertex (in eye coordinates). Let n'
be the current normal, after transformation to eye coordinates. Let
T
f = (f f f ) be the reflection vector such that
x y z
T
f = u - 2n'n' u
_____________
| 2 2 2
Finally, let m = 2\|f +f +(f +1) . Then the values assigned to the s and
x y z
t texture coordinates are
f
x 1
s = --- + -
m 2
f
y 1
t = --- + -
m 2
A texture-coordinate generation function is enabled or disabled using
glEnable or glDisable with one of the symbolic texture-coordinate names
(GL_TEXTURE_GEN_S, GL_TEXTURE_GEN_T, GL_TEXTURE_GEN_R, or GL_TEXTURE_GEN_Q)
as the argument. When enabled, the specified texture coordinate is computed
according to the generating function associated with that coordinate. When
disabled, subsequent vertices take the specified texture coordinate from
the current set of texture coordinates. Initially, all texture generation
functions are set to GL_EYE_LINEAR and are disabled. Both s plane
equations are (1,0,0,0), both t plane equations are (0,1,0,0), and all r
and q plane equations are (0,0,0,0).
Errors
GL_INVALID_ENUM is generated when coord or pname is not an accepted defined
value, or when pname is GL_TEXTURE_GEN_MODE and params is not an accepted
defined value.
GL_INVALID_ENUM is generated when pname is GL_TEXTURE_GEN_MODE, params is
GL_SPHERE_MAP, and coord is either GL_R or GL_Q.
GL_INVALID_OPERATION is generated if glTexGen is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetTexGen
glIsEnabled with argument GL_TEXTURE_GEN_S
glIsEnabled with argument GL_TEXTURE_GEN_T
glIsEnabled with argument GL_TEXTURE_GEN_R
glIsEnabled with argument GL_TEXTURE_GEN_Q
See Also
glTexEnv, glTexImage1D, glTexImage2D, glTexParameter
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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.111. glTexImage1D ΓòÉΓòÉΓòÉ
OpenGL man pages
glTexImage1D
Name
glTexImage1D - specify a one-dimensional texture image
C Specification
void glTexImage1D( GLenum target,
GLint level,
GLint components,
GLsizei width,
GLint border,
GLenum format,
GLenum type,
const GLvoid *pixels )
Parameters
target Specifies the target texture. Must be GL_TEXTURE_1D.
level Specifies the level-of-detail number. Level 0 is the base
image level. Level n is the nth mipmap reduction image.
components Specifies the number of color components in the texture. Must
be 1, 2, 3, or 4.
n
width Specifies the width of the texture image. Must be 2 +2(border)
for some integer n. The height of the texture image is 1.
border Specifies the width of the border. Must be either 0 or 1.
format Specifies the format of the pixel data. The following symbolic
values are accepted: GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE,
GL_ALPHA, GL_RGB, GL_RGBA, GL_LUMINANCE, and
GL_LUMINANCE_ALPHA.
type Specifies the data type of the pixel data. The following
symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE,
GL_BITMAP, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT,
GL_INT, and GL_FLOAT.
pixels Specifies a pointer to the image data in memory.
Description
Texturing maps a portion of a specified texture image onto each graphical
primitive for which texturing is enabled. One-dimensional texturing is
enabled and disabled using glEnable and glDisable with argument
GL_TEXTURE_1D.
Texture images are defined with glTexImage1D. The arguments describe the
parameters of the texture image, such as width, width of the border,
level-of-detail number (see glTexParameter), and number of color components
provided. The last three arguments describe the way the image is
represented in memory, and they are identical to the pixel formats used for
glDrawPixels.
Data is read from pixels as a sequence of signed or unsigned bytes, shorts,
or longs, or single-precision floating-point values, depending on type.
These values are grouped into sets of one, two, three, or four values,
depending on format, to form elements. If type is GL_BITMAP, the data is
considered as a string of unsigned bytes (and format must be
GL_COLOR_INDEX). Each data byte is treated as eight 1-bit elements, with
bit ordering determined by GL_UNPACK_LSB_FIRST (see glPixelStore).
format determines the composition of each element in pixels. It can assume
one of nine symbolic values:
GL_COLOR_INDEX
Each element is a single value, a color index. It is converted to
fixed point (with an unspecified number of zero bits to the right
of the binary point), shifted left or right depending on the
value and sign of GL_INDEX_SHIFT, and added to GL_INDEX_OFFSET
(see glPixelTransfer). The resulting index is converted to a set
of color components using the GL_PIXEL_MAP_I_TO_R,
GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B, and GL_PIXEL_MAP_I_TO_A
tables, and clamped to the range [0,1].
GL_RED Each element is a single red component. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for green and blue, and 1.0 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE, added to the
signed bias GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_GREEN Each element is a single green component. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for red and blue, and 1.0 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE, added to the
signed bias GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_BLUE Each element is a single blue component. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for red and green, and 1.0 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE, added to the
signed bias GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_ALPHA Each element is a single alpha component. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for red, green, and blue. Each component is then multiplied
by the signed scale factor GL_c_SCALE, added to the signed bias
GL_c_BIAS, and clamped to the range [0,1] (see glPixelTransfer).
GL_RGB Each element is an RGB triple. It is converted to floating point
and assembled into an RGBA element by attaching 1.0 for alpha.
Each component is then multiplied by the signed scale factor
GL_c_SCALE, added to the signed bias GL_c_BIAS, and clamped to
the range [0,1] (see glPixelTransfer).
GL_RGBA Each element is a complete RGBA element. It is converted to
floating point. Each component is then multiplied by the signed
scale factor GL_c_SCALE, added to the signed bias GL_c_BIAS, and
clamped to the range [0,1] (see glPixelTransfer).
GL_LUMINANCE
Each element is a single luminance value. It is converted to
floating point, then assembled into an RGBA element by
replicating the luminance value three times for red, green, and
blue and attaching 1.0 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE, added to the
signed bias GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_LUMINANCE_ALPHA
Each element is a luminance/alpha pair. It is converted to
floating point, then assembled into an RGBA element by
replicating the luminance value three times for red, green, and
blue. Each component is then multiplied by the signed scale
factor GL_c_SCALE, added to the signed bias GL_c_BIAS, and
clamped to the range [0,1] (see glPixelTransfer).
A texture image can have up to four components per texture element,
depending on components. A one-component texture image uses only the red
component of the RGBA color extracted from pixels. A two-component image
uses the R and A values. A three-component image uses the R, G, and B
values. A four-component image uses all of the RGBA components.
Notes
Texturing has no effect in color index mode.
The texture image can be represented by the same data formats as the pixels
in a glDrawPixels command, except that GL_STENCIL_INDEX and
GL_DEPTH_COMPONENT cannot be used. glPixelStore and glPixelTransfer modes
affect texture images in exactly the way they affect glDrawPixels.
A texture image with zero width indicates the null texture. If the null
texture is specified for level-of-detail 0, it is as if texturing were
disabled.
Errors
GL_INVALID_ENUM is generated when target is not GL_TEXTURE_1D.
GL_INVALID_ENUM is generated when format is not an accepted format
constant. Format constants other than GL_STENCIL_INDEX and
GL_DEPTH_COMPONENT are accepted.
GL_INVALID_ENUM is generated when type is not a type constant.
GL_INVALID_ENUM is generated if type is GL_BITMAP and format is not
GL_COLOR_INDEX.
GL_INVALID_VALUE is generated if level is less than zero or greater than
log max, where max is the returned value of GL_MAX_TEXTURE_SIZE.
2
GL_INVALID_VALUE is generated if components is not 1, 2, 3, or 4.
GL_INVALID_VALUE is generated if width is less than zero or greater than
n
2 + GL_MAX_TEXTURE_SIZE, or if it cannot be represented as 2 +2(border) for
some integer value of n.
GL_INVALID_VALUE is generated if border is not 0 or 1.
GL_INVALID_OPERATION is generated if glTexImage1D is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetTexImage
glIsEnabled with argument GL_TEXTURE_1D
See Also
glDrawPixels, glFog, glPixelStore, glPixelTransfer, glTexEnv, glTexGen,
glTexImage2D, glTexParameter
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.112. glTexImage2D ΓòÉΓòÉΓòÉ
OpenGL man pages
glTexImage2D
Name
glTexImage2D - specify a two-dimensional texture image
C Specification
void glTexImage2D( GLenum target,
GLint level,
GLint components,
GLsizei width,
GLsizei height,
GLint border,
GLenum format,
GLenum type,
const GLvoid *pixels )
Parameters
target Specifies the target texture. Must be GL_TEXTURE_2D.
level Specifies the level-of-detail number. Level 0 is the base
image level. Level n is the nth mipmap reduction image.
components Specifies the number of color components in the texture. Must
be 1, 2, 3, or 4.
╨░ n
width Specifies the width of the texture image. Must be 2 +2(border)
for some integer n.
height Specifies the height of the texture image. Must be
m
2 +2(border) for some integer m.
border Specifies the width of the border. Must be either 0 or 1.
format Specifies the format of the pixel data. The following symbolic
values are accepted: GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE,
GL_ALPHA, GL_RGB, GL_RGBA, GL_LUMINANCE, and
GL_LUMINANCE_ALPHA.
type Specifies the data type of the pixel data. The following
symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE,
GL_BITMAP, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT,
GL_INT, and GL_FLOAT.
pixels Specifies a pointer to the image data in memory.
Description
Texturing maps a portion of a specified texture image onto each graphical
primitive for which texturing is enabled. Two-dimensional texturing is
enabled and disabled using glEnable and glDisable with argument
GL_TEXTURE_2D.
Texture images are defined with glTexImage2D. The arguments describe the
parameters of the texture image, such as height, width, width of the
border, level-of-detail number (see glTexParameter), and number of color
components provided. The last three arguments describe the way the image
is represented in memory, and they are identical to the pixel formats used
for glDrawPixels.
Data is read from pixels as a sequence of signed or unsigned bytes, shorts,
or longs, or single-precision floating-point values, depending on type.
These values are grouped into sets of one, two, three, or four values,
depending on format, to form elements. If type is GL_BITMAP, the data is
considered as a string of unsigned bytes (and format must be
GL_COLOR_INDEX). Each data byte is treated as eight 1-bit elements, with
bit ordering determined by GL_UNPACK_LSB_FIRST (see glPixelStore).
format determines the composition of each element in pixels. It can assume
one of nine symbolic values:
GL_COLOR_INDEX
Each element is a single value, a color index. It is converted to
fixed point (with an unspecified number of zero bits to the right
of the binary point), shifted left or right depending on the
value and sign of GL_INDEX_SHIFT, and added to GL_INDEX_OFFSET
(see glPixelTransfer). The resulting index is converted to a set
of color components using the GL_PIXEL_MAP_I_TO_R,
GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B, and GL_PIXEL_MAP_I_TO_A
tables, and clamped to the range [0,1].
GL_RED Each element is a single red component. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for green and blue, and 1.0 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE, added to the
signed bias GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_GREEN Each element is a single green component. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for red and blue, and 1.0 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE, added to the
signed bias GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_BLUE Each element is a single blue component. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for red and green, and 1.0 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE, added to the
signed bias GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_ALPHA Each element is a single alpha component. It is converted to
floating point and assembled into an RGBA element by attaching
0.0 for red, green, and blue. Each component is then multiplied
by the signed scale factor GL_c_SCALE, added to the signed bias
GL_c_BIAS, and clamped to the range [0,1] (see glPixelTransfer).
GL_RGB Each element is an RGB triple. It is converted to floating point
and assembled into an RGBA element by attaching 1.0 for alpha.
Each component is then multiplied by the signed scale factor
GL_c_SCALE, added to the signed bias GL_c_BIAS, and clamped to
the range [0,1] (see glPixelTransfer).
GL_RGBA Each element is a complete RGBA element. It is converted to
floating point. Each component is then multiplied by the signed
scale factor GL_c_SCALE, added to the signed bias GL_c_BIAS, and
clamped to the range [0,1] (see glPixelTransfer).
GL_LUMINANCE
Each element is a single luminance value. It is converted to
floating point, then assembled into an RGBA element by
replicating the luminance value three times for red, green, and
blue and attaching 1.0 for alpha. Each component is then
multiplied by the signed scale factor GL_c_SCALE, added to the
signed bias GL_c_BIAS, and clamped to the range [0,1] (see
glPixelTransfer).
GL_LUMINANCE_ALPHA
Each element is a luminance/alpha pair. It is converted to
floating point, then assembled into an RGBA element by
replicating the luminance value three times for red, green, and
blue. Each component is then multiplied by the signed scale
factor GL_c_SCALE, added to the signed bias GL_c_BIAS, and
clamped to the range [0,1] (see glPixelTransfer).
Please refer to the glDrawPixels reference page for a description of the
acceptable values for the type parameter. A texture image can have up to
four components per texture element, depending on components. A one-
component texture image uses only the red component of the RGBA color
extracted from pixels. A two-component image uses the R and A values. A
three-component image uses the R, G, and B values. A four-component image
uses all of the RGBA components.
Notes
Texturing has no effect in color index mode.
The texture image can be represented by the same data formats as the pixels
in a glDrawPixels command, except that GL_STENCIL_INDEX and
GL_DEPTH_COMPONENT cannot be used. glPixelStore and glPixelTransfer modes
affect texture images in exactly the way they affect glDrawPixels.
A texture image with zero height or width indicates the null texture. If
the null texture is specified for level-of-detail 0, it is as if texturing
were disabled.
Errors
GL_INVALID_ENUM is generated when target is not GL_TEXTURE_2D.
GL_INVALID_ENUM is generated when format is not an accepted format
constant. Format constants other than GL_STENCIL_INDEX and
GL_DEPTH_COMPONENT are accepted.
GL_INVALID_ENUM is generated when type is not a type constant.
GL_INVALID_ENUM is generated if type is GL_BITMAP and format is not
GL_COLOR_INDEX.
GL_INVALID_VALUE is generated if level is less than zero or greater than
log max, where max is the returned value of GL_MAX_TEXTURE_SIZE.
2
GL_INVALID_VALUE is generated if components is not 1, 2, 3, or 4.
GL_INVALID_VALUE is generated if width or height is less than zero or
greater than 2 + GL_MAX_TEXTURE_SIZE, or if either cannot be represented as
k
2 +2(border) for some integer value of k.
GL_INVALID_VALUE is generated if border is not 0 or 1.
GL_INVALID_OPERATION is generated if glTexImage2D is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGetTexImage
glIsEnabled with argument GL_TEXTURE_2D
See Also
glDrawPixels, glFog, glPixelStore, glPixelTransfer, glTexEnv, glTexGen,
glTexImage1D, glTexParameter
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.113. glTexParameter ΓòÉΓòÉΓòÉ
OpenGL man pages
glTexParameter
Name
glTexParameterf, glTexParameteri, glTexParameterfv, glTexParameteriv - set
texture parameters
C Specification
void glTexParameterf( GLenum target,
GLenum pname,
GLfloat param )
void glTexParameteri( GLenum target,
GLenum pname,
GLint param )
Parameters
target Specifies the target texture, which must be either GL_TEXTURE_1D or
GL_TEXTURE_2D.
pname Specifies the symbolic name of a single-valued texture parameter.
pname can be one of the following: GL_TEXTURE_MIN_FILTER,
GL_TEXTURE_MAG_FILTER, GL_TEXTURE_WRAP_S, or GL_TEXTURE_WRAP_T.
param Specifies the value of pname.
C Specification
void glTexParameterfv( GLenum target,
GLenum pname,
const GLfloat *params )
void glTexParameteriv( GLenum target,
GLenum pname,
const GLint *params )
Parameters
target
Specifies the target texture, which must be either GL_TEXTURE_1D or
GL_TEXTURE_2D.
pname
Specifies the symbolic name of a texture parameter. pname can be one
of the following: GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MAG_FILTER,
GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T, or GL_TEXTURE_BORDER_COLOR.
params
Specifies a pointer to an array where the value or values of pname are
stored.
Description
Texture mapping is a technique that applies an image onto an object's
surface as if the image were a decal or cellophane shrink-wrap. The image
is created in texture space, with an (s, t) coordinate system. A texture is
a one- or two-dimensional image and a set of parameters that determine how
samples are derived from the image.
glTexParameter assigns the value or values in params to the texture
parameter specified as pname. target defines the target texture, either
GL_TEXTURE_1D or GL_TEXTURE_2D. The following symbols are accepted in
pname:
GL_TEXTURE_MIN_FILTER
The texture minifying function is used whenever the pixel being
textured maps to an area greater than one texture element. There
are six defined minifying functions. Two of them use the nearest
one or nearest four texture elements to compute the texture
value. The other four use mipmaps.
A mipmap is an ordered set of arrays representing the same image
at progressively lower resolutions. If the texture has dimensions
2nx2m there are max(n,m)+1 mipmaps. The first mipmap is the
original texture, with dimensions 2nx2m. Each subsequent mipmap
has dimensions 2k-1x2l-1 where 2kx2l are the dimensions of the
previous mipmap, until either k=0 or l=0. At that point,
subsequent mipmaps have dimension 1x2l-1 or 2k-1x1 until the
final mipmap, which has dimension 1x1. Mipmaps are defined using
glTexImage1D or glTexImage2D with the level-of-detail argument
indicating the order of the mipmaps. Level 0 is the original
texture; level max(n,m) is the final 1x1 mipmap.
params supplies a function for minifying the texture as one of
the following:
GL_NEAREST
Returns the value of the texture element that is
nearest (in Manhattan distance) to the center of the
pixel being textured.
GL_LINEAR Returns the weighted average of the four texture
elements that are closest to the center of the pixel
being textured. These can include border texture
elements, depending on the values of GL_TEXTURE_WRAP_S
and GL_TEXTURE_WRAP_T, and on the exact mapping.
GL_NEAREST_MIPMAP_NEAREST
Chooses the mipmap that most closely matches the size
of the pixel being textured and uses the GL_NEAREST
criterion (the texture element nearest to the center of
the pixel) to produce a texture value.
GL_LINEAR_MIPMAP_NEAREST
Chooses the mipmap that most closely matches the size
of the pixel being textured and uses the GL_LINEAR
criterion (a weighted average of the four texture
elements that are closest to the center of the pixel)
to produce a texture value.
GL_NEAREST_MIPMAP_LINEAR
Chooses the two mipmaps that most closely match the
size of the pixel being textured and uses the
GL_NEAREST criterion (the texture element nearest to
the center of the pixel) to produce a texture value
from each mipmap. The final texture value is a weighted
average of those two values.
GL_LINEAR_MIPMAP_LINEAR
Chooses the two mipmaps that most closely match the
size of the pixel being textured and uses the GL_LINEAR
criterion (a weighted average of the four texture
elements that are closest to the center of the pixel)
to produce a texture value from each mipmap. The final
texture value is a weighted average of those two
values.
As more texture elements are sampled in the minification process,
fewer aliasing artifacts will be apparent. While the GL_NEAREST
and GL_LINEAR minification functions can be faster than the other
four, they sample only one or four texture elements to determine
the texture value of the pixel being rendered and can produce
moire patterns or ragged transitions. The default value of
GL_TEXTURE_MIN_FILTER is GL_NEAREST_MIPMAP_LINEAR.
GL_TEXTURE_MAG_FILTER
The texture magnification function is used when the pixel being
textured maps to an area less than or equal to one texture
element. It sets the texture magnification function to either of
the following:
GL_NEAREST
Returns the value of the texture element that is
nearest (in Manhattan distance) to the center of the
pixel being textured.
GL_LINEAR Returns the weighted average of the four
texture elements that are closest to the center of the
pixel being textured. These can include border texture
elements, depending on the values of GL_TEXTURE_WRAP_S
and GL_TEXTURE_WRAP_T, and on the exact mapping.
GL_NEAREST is generally faster than GL_LINEAR, but it can produce
textured images with sharper edges because the transition between
texture elements is not as smooth. The default value of
GL_TEXTURE_MAG_FILTER is GL_LINEAR.
GL_TEXTURE_WRAP_S
Sets the wrap parameter for texture coordinate s to either
GL_CLAMP or GL_REPEAT. GL_CLAMP causes s coordinates to be
clamped to the range [0,1] and is useful for preventing wrapping
artifacts when mapping a single image onto an object. GL_REPEAT
causes the integer part of the s coordinate to be ignored; the GL
uses only the fractional part, thereby creating a repeating
pattern. Border texture elements are accessed only if wrapping is
set to GL_CLAMP. Initially, GL_TEXTURE_WRAP_S is set to
GL_REPEAT.
GL_TEXTURE_WRAP_T
Sets the wrap parameter for texture coordinate t to either
GL_CLAMP or GL_REPEAT. See the discussion under
GL_TEXTURE_WRAP_S. Initially, GL_TEXTURE_WRAP_T is set to
GL_REPEAT.
GL_TEXTURE_BORDER_COLOR
Sets a border color. params contains four values that comprise
the RGBA color of the texture border. Integer color components
are interpreted linearly such that the most positive integer maps
to 1.0, and the most negative integer maps to -1.0. The values
are clamped to the range [0,1] when they are specified.
Initially, the border color is (0, 0, 0, 0).
Notes
Suppose texturing is enabled (by calling glEnable with argument
GL_TEXTURE_1D or GL_TEXTURE_2D) and GL_TEXTURE_MIN_FILTER is set to one of
the functions that requires a mipmap. If either the dimensions of the
texture images currently defined (with previous calls to glTexImage1D or
glTexImage2D) do not follow the proper sequence for mipmaps (described
above), or there are fewer texture images defined than are needed, or the
set of texture images have differing numbers of texture components, then it
is as if texture mapping were disabled.
Linear filtering accesses the four nearest texture elements only in 2-D
textures. In 1-D textures, linear filtering accesses the two nearest
texture elements.
Errors
GL_INVALID_ENUM is generated when target or pname is not one of the
accepted defined values, or when params should have a defined constant
value (based on the value of pname) and does not.
GL_INVALID_OPERATION is generated if glTexParameter is called between a
call to glBegin and the corresponding call to glEnd.
Associated Gets
glGetTexParameter
glGetTexLevelParameter
See Also
glTexEnv, glTexImage1D, glTexImage2D, glTexGen
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ΓòÉΓòÉΓòÉ 3.114. glTranslate ΓòÉΓòÉΓòÉ
OpenGL man pages
glTranslate
Name
glTranslated, glTranslatef - multiply the current matrix by a translation
matrix
C Specification
void glTranslated( GLdouble x,
GLdouble y,
GLdouble z )
void glTranslatef( GLfloat x,
GLfloat y,
GLfloat z )
Parameters
x, y, z
Specify the x, y, and z coordinates of a translation vector.
Description
glTranslate moves the coordinate system origin to the point specified by
(x,y,z). The translation vector is used to compute a 4x4 translation
matrix:
| 1 0 0 x |
| |
| 0 1 0 y |
| |
| 0 0 1 z |
| |
| 0 0 0 1 |
The current matrix (see glMatrixMode) is multiplied by this translation
matrix, with the product replacing the current matrix. That is, if M is
the current matrix and T is the translation matrix, then M is replaced with
M Γòû T.
If the matrix mode is either GL_MODELVIEW or GL_PROJECTION, all objects
drawn after glTranslate is called are translated. Use glPushMatrix and
glPopMatrix to save and restore the untranslated coordinate system.
Errors
GL_INVALID_OPERATION is generated if glTranslate is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_MATRIX_MODE
glGet with argument GL_MODELVIEW_MATRIX
glGet with argument GL_PROJECTION_MATRIX
glGet with argument GL_TEXTURE_MATRIX
See Also
glMatrixMode, glMultMatrix, glPushMatrix, glRotate, glScale
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ΓòÉΓòÉΓòÉ 3.115. glVertex ΓòÉΓòÉΓòÉ
OpenGL man pages
glVertex
Name
glVertex2d, glVertex2f, glVertex2i, glVertex2s, glVertex3d,
glVertex3f,
glVertex3i, glVertex3s, glVertex4d, glVertex4f, glVertex4i,
glVertex4s,
glVertex2dv, glVertex2fv, glVertex2iv, glVertex2sv, glVertex3dv,
glVertex3fv, glVertex3iv, glVertex3sv, glVertex4dv, glVertex4fv,
glVertex4iv, glVertex4sv - specify a vertex
C Specification
void glVertex2d( GLdouble x,
GLdouble y )
void glVertex2f( GLfloat x,
GLfloat y )
void glVertex2i( GLint x,
GLint y )
void glVertex2s( GLshort x,
GLshort y )
void glVertex3d( GLdouble x,
GLdouble y,
GLdouble z )
void glVertex3f( GLfloat x,
GLfloat y,
GLfloat z )
void glVertex3i( GLint x,
GLint y,
GLint z )
void glVertex3s( GLshort x,
GLshort y,
GLshort z )
void glVertex4d( GLdouble x,
GLdouble y,
GLdouble z,
GLdouble w )
void glVertex4f( GLfloat x,
GLfloat y,
GLfloat z,
GLfloat w )
void glVertex4i( GLint x,
GLint y,
GLint z,
GLint w )
void glVertex4s( GLshort x,
GLshort y,
GLshort z,
GLshort w )
Parameters
x, y, z, w
Specify x, y, z, and w coordinates of a vertex. Not all
parameters are present in all forms of the command.
C Specification
void glVertex2dv( const GLdouble *v )
void glVertex2fv( const GLfloat *v )
void glVertex2iv( const GLint *v )
void glVertex2sv( const GLshort *v )
void glVertex3dv( const GLdouble *v )
void glVertex3fv( const GLfloat *v )
void glVertex3iv( const GLint *v )
void glVertex3sv( const GLshort *v )
void glVertex4dv( const GLdouble *v )
void glVertex4fv( const GLfloat *v )
void glVertex4iv( const GLint *v )
void glVertex4sv( const GLshort *v )
Parameters
v Specifies a pointer to an array of two, three, or four elements. The
elements of a two-element array are x and y; of a three-element array,
x, y, and z; and of a four-element array, x, y, z, and w.
Description
glVertex commands are used within glBegin/glEnd pairs to specify point,
line, and polygon vertices. The current color, normal, and texture
coordinates are associated with the vertex when glVertex is called.
When only x and y are specified, z defaults to 0.0 and w defaults to 1.0.
When x, y, and z are specified, w defaults to 1.0.
Notes
Invoking glVertex outside of a glBegin/glEnd pair results in undefined
behavior.
See Also
glBegin, glCallList, glColor, glEdgeFlag, glEvalCoord, glIndex, glMaterial,
glNormal, glRect, glTexCoord
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ΓòÉΓòÉΓòÉ 3.116. glVertexPointerEXT ΓòÉΓòÉΓòÉ
OpenGL man pages
glVertexPointerEXT
Name
glVertexPointerEXT - define an array of vertex data
C Specification
void glVertexPointerEXT( GLint size,
GLenum type,
GLsizei stride,
GLsizei count,
const GLvoid *pointer )
Parameters
size Specifies the number of coordinates per vertex, must be 2,3, or 4.
type Specifies the data type of each coordinate in the array. Symbolic
constants GL_SHORT, GL_INT, GL_FLOAT, or GL_DOUBLE_EXT are
accepted.
stride Specifies the byte offset between consecutive vertexes. If stride
is 0 the vertexes are understood to be tightly packed in the
array.
count Specifies the number of vertexes, counting from the first, that
are static.
pointer Specifies a pointer to the first coordinate of the first vertex in
the array.
Description
glVertexPointerEXT specifies the location and data format of an array of
vertex coordinates to use when rendering using the vertex array extension.
size specifies the number of coordinates per vertex and type the
data type of the coordinates. stride gives the byte stride from one vertex
to the next allowing vertexes and attributes to be packed into a single
array or stored in separate arrays. (Single-array storage may be more
efficient on some implementations.) count indicates the number of array
elements (counting from the first) that are static. Static elements may be
modified by the application, but once they are modified, the application
must explicitly respecify the array before using it for any rendering. When
a vertex array is specified, size, type, stride, count, and pointer are saved
as client-side state, and static array elements may be cached by the
implementation.
The vertex array is enabled and disabled using glEnable and glDisable with
the argument GL_VERTEX_ARRAY_EXT. If enabled, the vertex array is used when
glDrawArraysEXT or glArrayElementEXT is called.
Use glDrawArraysEXT to define a sequence of primitives (all of the same
type) from pre-specified vertex and vertex attribute arrays. Use
glArrayElementEXT to specify primitives by indexing vertexes and vertex
attributes.
Notes
Non-static array elements are not accessed until glArrayElementEXT or
glDrawArraysEXT is executed.
By default the vertex array is disabled and it won't be accessed when
glArrayElementEXT or glDrawArraysEXT is called.
Although it is not an error to call glVertexPointerEXT between the
execution of glBegin and the corresponding execution of glEnd, the results
are undefined.
glVertexPointerEXT will typically be implemented on the client side with no
protocol.
Since the vertex array parameters are client side state, they are not saved
or restored by glPushAttrib and glPopAttrib.
glVertexPointerEXT commands are not entered into display lists.
glVertexPointerEXT is part of the EXT_vertex_array extension, not
part of the core GL command set. If "GL_EXT_vertex_array" is
included in the string returned by glGetString, when called with argument
GL_EXTENSIONS, extension EXT_vertex_array is supported.
Errors
GL_INVALID_VALUE is generated if size is not 2, 3, or 4.
GL_INVALID_ENUM is generated if type is is not an accepted value.
GL_INVALID_VALUE is generated if stride or count is negative.
Associated Gets
glIsEnabled with argument GL_VERTEX_ARRAY_EXT
glGet with argument GL_VERTEX_ARRAY_SIZE_EXT
glGet with argument GL_VERTEX_ARRAY_TYPE_EXT
glGet with argument GL_VERTEX_ARRAY_STRIDE_EXT
glGet with argument GL_VERTEX_ARRAY_COUNT_EXT
glGetPointervEXT with argument GL_VERTEX_ARRAY_POINTER_EXT
See Also
glArrayElementEXT, glColorPointerEXT, glDrawArraysEXT,
glEdgeFlagPointerEXT, glGetPointervEXT, glIndexPointerEXT,
glNormalPointerEXT, glTexCoordPointerEXT, glEnable
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ΓòÉΓòÉΓòÉ 3.117. glViewport ΓòÉΓòÉΓòÉ
OpenGL man pages
glViewport
Name
glViewport - set the viewport
C Specification
void glViewport( GLint x,
GLint y,
GLsizei width,
GLsizei height )
Parameters
x, y Specify the lower left corner of the viewport rectangle, in pixels.
The default is (0,0).
width, height
Specify the width and height, respectively, of the viewport. When a
GL context is first attached to a window, width and height are set to
the dimensions of that window.
Description
glViewport specifies the affine transformation of x and y from normalized
device coordinates to window coordinates. Let (x , y ) be normalized
nd nd
device coordinates. Then the window coordinates x , y ) are computed as
follows: w w
width
x = (x +1)----- + x
w nd 2
height
y = (y +1)------ + y
w nd 2
Viewport width and height are silently clamped to a range that depends on
the implementation. This range is queried by calling glGet with argument
GL_MAX_VIEWPORT_DIMS.
Errors
GL_INVALID_VALUE is generated if either width or height is negative.
GL_INVALID_OPERATION is generated if glViewport is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_VIEWPORT
glGet with argument GL_MAX_VIEWPORT_DIMS
See Also
glDepthRange
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ΓòÉΓòÉΓòÉ 3.118. glXChooseVisual ΓòÉΓòÉΓòÉ
OpenGL man pages
glXChooseVisual
Name
glXChooseVisual - return a visual that matches specified attributes
C Specification
XVisualInfo* glXChooseVisual( Display *dpy,
int screen,
int *attribList )
Parameters
dpy Specifies the connection to the X server.
screen Specifies the screen number.
attribList Specifies a list of Boolean attributes and integer
attribute/value pairs. The last attribute must be None.
Description
glXChooseVisual returns a pointer to an XVisualInfo structure describing
the visual that best meets a minimum specification. The Boolean GLX
attributes of the visual that is returned will match the specified values,
and the integer GLX attributes will meet or exceed the specified minimum
values. If all other attributes are equivalent, then TrueColor and
PseudoColor visuals have priority over DirectColor and StaticColor visuals,
respectively. If no conforming visual exists, NULL is returned. To free
the data returned by this function, use XFree.
All Boolean GLX attributes default to False except GLX_USE_GL, which
defaults to True. All integer GLX attributes default to zero. Default
specifications are superseded by attributes included in attribList.
Boolean attributes included in attribList are understood to be True.
Integer attributes are followed immediately by the corresponding desired or
minimum value. The list must be terminated with None.
The interpretations of the various GLX visual attributes are as follows:
GLX_USE_GL Ignored. Only visuals that can be rendered with GLX
are considered.
GLX_BUFFER_SIZE Must be followed by a nonnegative integer that
indicates the desired color index buffer size. The
smallest index buffer of at least the specified size
is preferred. Ignored if GLX_RGBA is asserted.
GLX_LEVEL Must be followed by an integer buffer-level
specification. This specification is honored
exactly. Buffer level zero corresponds to the
default frame buffer of the display. Buffer level
one is the first overlay frame buffer, level two the
second overlay frame buffer, and so on. Negative
buffer levels correspond to underlay frame buffers.
GLX_RGBA If present, only TrueColor and DirectColor visuals
are considered. Otherwise, only PseudoColor and
StaticColor visuals are considered.
GLX_DOUBLEBUFFER If present, only double-buffered visuals are
considered. Otherwise, only single-buffered visuals
are considered.
GLX_STEREO If present, only stereo visuals are considered.
Otherwise, only monoscopic visuals are considered.
GLX_AUX_BUFFERS Must be followed by a nonnegative integer that
indicates the desired number of auxiliary buffers.
Visuals with the smallest number of auxiliary
buffers that meets or exceeds the specified number
are preferred.
GLX_RED_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, the smallest
available red buffer is preferred. Otherwise, the
largest available red buffer of at least the minimum
size is preferred.
GLX_GREEN_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, the smallest
available green buffer is preferred. Otherwise, the
largest available green buffer of at least the
minimum size is preferred.
GLX_BLUE_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, the smallest
available blue buffer is preferred. Otherwise, the
largest available blue buffer of at least the minimum
size is preferred.
GLX_ALPHA_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, the smallest
available alpha buffer is preferred. Otherwise, the
largest available alpha buffer of at least the
minimum size is preferred.
GLX_DEPTH_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, visuals with
no depth buffer are preferred. Otherwise, the
largest available depth buffer of at least the
minimum size is preferred.
GLX_STENCIL_SIZE Must be followed by a nonnegative integer that
indicates the desired number of stencil bitplanes.
The smallest stencil buffer of at least the specified
size is preferred. If the desired value is zero,
visuals with no stencil buffer are preferred.
GLX_ACCUM_RED_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, visuals with
no red accumulation buffer are preferred. Otherwise,
the largest possible red accumulation buffer of at
least the minimum size is preferred.
GLX_ACCUM_GREEN_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, visuals with
no green accumulation buffer are preferred.
Otherwise, the largest possible green accumulation
buffer of at least the minimum size is preferred.
GLX_ACCUM_BLUE_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, visuals with
no blue accumulation buffer are preferred.
Otherwise, the largest possible blue accumulation
buffer of at least the minimum size is preferred.
GLX_ACCUM_ALPHA_SIZE Must be followed by a nonnegative minimum size
specification. If this value is zero, visuals with
no alpha accumulation buffer are preferred.
Otherwise, the largest possible alpha accumulation
buffer of at least the minimum size is preferred.
Examples
attribList =
{GLX_RGBA, GLX_RED_SIZE, 4, GLX_GREEN_SIZE, 4, GLX_BLUE_SIZE,
4, None};
Specifies a single-buffered RGB visual in the normal frame buffer, not an
overlay or underlay buffer. The returned visual supports at least four
bits each of red, green, and blue, and possibly no bits of alpha. It does
not support color index mode, double-buffering, or stereo display. It may
or may not have one or more auxiliary color buffers, a depth buffer, a
stencil buffer, or an accumulation buffer.
Notes
XVisualInfo is defined in Xutil.h. It is a structure that includes visual,
visualID, screen, and depth elements.
glXChooseVisual is implemented as a client-side utility using only
XGetVisualInfo and glXGetConfig. Calls to these two routines can be used
to implement selection algorithms other than the generic one implemented by
glXChooseVisual.
GLX implementers are strongly discouraged, but not proscribed, from
changing the selection algorithm used by glXChooseVisual. Therefore,
selections may change from release to release of the client-side library.
There is no direct filter for picking only visuals that support GLXPixmaps.
GLXPixmaps are supported for visuals whose GLX_BUFFER_SIZE. is one of the
Pixmap depths supported by the X server.
Errors
NULL is returned if an undefined GLX attribute is encountered in
attribList.
See Also
glXCreateContext, glXGetConfig
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ΓòÉΓòÉΓòÉ 3.119. glXCopyContext ΓòÉΓòÉΓòÉ
OpenGL man pages
glXCopyContext
Name
glXCopyContext - copy state from one rendering context to another
C Specification
void glXCopyContext( Display *dpy,
GLXContext src,
GLXContext dst,
GLuint mask )
Parameters
dpy Specifies the connection to the X server.
src Specifies the source context.
dst Specifies the destination context.
mask Specifies which portions of src state are to be copied to dst.
Description
glXCopyContext copies selected groups of state variables from src to dst.
mask indicates which groups of state variables are to be copied. mask
contains the bitwise OR of the same symbolic names that are passed to the
OpenGL command glPushAttrib. The single symbolic constant
GL_ALL_ATTRIB_BITS can be used to copy the maximum possible portion of
rendering state.
The copy can be done only if the renderers named by src and dst share an
address space. Two rendering contexts share an address space if both are
nondirect using the same server, or if both are direct and owned by a
single process. Note that in the nondirect case it is not necessary for
the calling threads to share an address space, only for their related
rendering contexts to share an address space.
Not all values for OpenGL state can be copied. For example, pixel pack and
unpack state, render mode state, and select and feedback state are not
copied. The state that can be copied is exactly the state that is
manipulated by OpenGL command glPushAttrib.
An implicit glFlush is done by glXCopyContext if src is the current context
for the calling thread.
If src is not the current context for the thread issuing the request, then
the state of the src context is undefined.
Notes
Two rendering contexts share an address space if both are nondirect using
the same server, or if both are direct and owned by a single process.
A process is a single execution environment, implemented in a single
address space, consisting of one or more threads.
A thread is one of a set of subprocesses that share a single address space,
but maintain separate program counters, stack spaces, and other related
global data. A thread that is the only member of its subprocess group is
equivalent to a process.
Errors
BadMatch is generated if rendering contexts src and dst do not share an
address space or were not created with respect to the same screen.
BadAccess is generated if dst is current to any thread (including the
calling thread) at the time glXCopyContext is called.
GLXBadCurrentWindow is generated if src is the current context and the
current drawable is a window that is no longer valid.
GLXBadContext is generated if either src or dst is not a valid GLX context.
BadValue is generated if undefined mask bits are specified.
See Also
glPushAttrib, glXCreateContext, glXIsDirect
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ΓòÉΓòÉΓòÉ 3.120. glXCreateContext ΓòÉΓòÉΓòÉ
OpenGL man pages
glXCreateContext
Name
glXCreateContext - create a new GLX rendering context
C Specification
GLXContext glXCreateContext( Display *dpy,
XVisualInfo *vis,
GLXContext shareList,
Bool direct )
Parameters
dpy Specifies the connection to the X server.
vis Specifies the visual that defines the frame buffer resources
available to the rendering context. It is a pointer to an
XVisualInfo structure, not a visual ID or a pointer to a Visual.
shareList Specifies the context with which to share display lists. NULL
indicates that no sharing is to take place.
direct Specifies whether rendering is to be done with a direct
connection to the graphics system if possible (True) or through
the X server (False).
Description
glXCreateContext creates a GLX rendering context and returns its handle.
This context can be used to render into both windows and GLX pixmaps. If
glXCreateContext fails to create a rendering context, NULL is returned.
If direct is True, then a direct rendering context is created if the
implementation supports direct rendering and the connection is to an X
server that is local. If direct is False, then a rendering context that
renders through the X server is always created. Direct rendering provides
a performance advantage in some implementations. However, direct rendering
contexts cannot be shared outside a single process, and they cannot be used
to render to GLX pixmaps.
If shareList is not NULL, then all display-list indexes and definitions are
shared by context shareList and by the newly created context. An arbitrary
number of contexts can share a single display-list space. However, all
rendering contexts that share a single display-list space must themselves
exist in the same address space. Two rendering contexts share an address
space if both are nondirect using the same server, or if both are direct
and owned by a single process. Note that in the nondirect case, it is not
necessary for the calling threads to share an address space, only for their
related rendering contexts to share an address space.
Notes
XVisualInfo is defined in Xutil.h. It is a structure that includes visual,
visualID, screen, and depth elements.
A process is a single execution environment, implemented in a single
address space, consisting of one or more threads.
A thread is one of a set of subprocesses that share a single address space,
but maintain separate program counters, stack spaces, and other related
global data. A thread that is the only member of its subprocess group is
equivalent to a process.
Errors
NULL is returned if execution fails on the client side.
BadMatch is generated if the context to be created would not share the
address space or the screen of the context specified by shareList.
BadValue is generated if vis is not a valid visual (e.g., if the GLX
implementation does not support it).
GLXBadContext is generated if shareList is not a GLX context and is not
NULL.
BadAlloc is generated if the server does not have enough resources to
allocate the new context.
See Also
glXDestroyContext, glXGetConfig, glXIsDirect, glXMakeCurrent
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ΓòÉΓòÉΓòÉ 3.121. glXCreateGLXPixmap ΓòÉΓòÉΓòÉ
OpenGL man pages
glXCreateGLXPixmap
Name
glXCreateGLXPixmap - create an off-screen GLX rendering area
C Specification
GLXPixmap glXCreateGLXPixmap( Display *dpy,
XVisualInfo *vis,
Pixmap pixmap )
Parameters
dpy Specifies the connection to the X server.
vis Specifies the visual that defines the structure of the rendering
area. It is a pointer to an XVisualInfo structure, not a visual ID
or a pointer to a Visual.
pixmap Specifies the X pixmap that will be used as the front left color
buffer of the off-screen rendering area.
Description
glXCreateGLXPixmap creates an off-screen rendering area and returns its
XID. Any GLX rendering context that was created with respect to vis can be
used to render into this off-screen area. Use glXMakeCurrent to associate
the rendering area with a GLX rendering context.
The X pixmap identified by pixmap is used as the front left buffer of the
resulting off-screen rendering area. All other buffers specified by vis,
including color buffers other than the front left buffer, are created
without externally visible names. GLX pixmaps with double-buffering are
supported. However, glXSwapBuffers is ignored by these pixmaps.
Direct rendering contexts cannot be used to render into GLX pixmaps.
Notes
XVisualInfo is defined in Xutil.h. It is a structure that includes visual,
visualID, screen, and depth elements.
Errors
BadMatch is generated if the depth of pixmap does not match the
GLX_BUFFER_SIZE value of vis, or if pixmap was not created with respect to
the same screen as vis.
BadValue is generated if vis is not a valid XVisualInfo pointer (e.g., if
the GLX implementation does not support this visual).
BadPixmap is generated if pixmap is not a valid pixmap.
BadAlloc is generated if the server cannot allocate the GLX pixmap.
See Also
glXCreateContext, glXIsDirect, glXMakeCurrent
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ΓòÉΓòÉΓòÉ 3.122. glXDestroyContext ΓòÉΓòÉΓòÉ
OpenGL man pages
glXDestroyContext
Name
glXDestroyContext - destroy a GLX context
C Specification
void glXDestroyContext( Display *dpy,
GLXContext ctx )
Parameters
dpy Specifies the connection to the X server.
ctx Specifies the GLX context to be destroyed.
Description
If GLX rendering context ctx is not current to any thread,
glXDestroyContext destroys it immediately. Otherwise, ctx is destroyed
when it becomes not current to any thread. In either case, the resource ID
referenced by ctx is freed immediately.
Errors
GLXBadContext is generated if ctx is not a valid GLX context.
See Also
glXCreateContext, glXMakeCurrent
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ΓòÉΓòÉΓòÉ 3.123. glXDestroyGLXPixmap ΓòÉΓòÉΓòÉ
OpenGL man pages
glXDestroyGLXPixmap
Name
glXDestroyGLXPixmap - destroy a GLX pixmap
C Specification
void glXDestroyGLXPixmap( Display *dpy,
GLXPixmap pix )
Parameters
dpy Specifies the connection to the X server.
pix Specifies the GLX pixmap to be destroyed.
Description
If GLX pixmap pix is not current to any client, glXDestroyGLXPixmap
destroys it immediately. Otherwise, pix is destroyed when it becomes not
current to any client. In either case, the resource ID is freed
immediately.
Errors
GLXBadPixmap is generated if pix is not a valid GLX pixmap.
See Also
glXCreateGLXPixmap, glXMakeCurrent
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ΓòÉΓòÉΓòÉ 3.124. glXGetConfig ΓòÉΓòÉΓòÉ
OpenGL man pages
glXGetConfig
Name
glXGetConfig - return information about GLX visuals
C Specification
int glXGetConfig( Display *dpy,
XVisualInfo *vis,
int attrib,
int *value )
Parameters
dpy Specifies the connection to the X server.
vis Specifies the visual to be queried. It is a pointer to an
XVisualInfo structure, not a visual ID or a pointer to a Visual.
attrib Specifies the visual attribute to be returned.
value Returns the requested value.
Description
glXGetConfig sets value to the attrib value of windows or GLX pixmaps
created with respect to vis. glXGetConfig returns an error code if it
fails for any reason. Otherwise, zero is returned.
attrib is one of the following:
GLX_USE_GL True if OpenGL rendering is supported by this visual,
False otherwise.
GLX_BUFFER_SIZE Number of bits per color buffer. For RGBA visuals,
GLX_BUFFER_SIZE is the sum of GLX_RED_SIZE,
GLX_GREEN_SIZE, GLX_BLUE_SIZE, and GLX_ALPHA_SIZE.
For color index visuals, GLX_BUFFER_SIZE is the size
of the color indexes.
GLX_LEVEL Frame buffer level of the visual. Level zero is the
default frame buffer. Positive levels correspond to
frame buffers that overlay the default buffer, and
negative levels correspond to frame buffers that
underlay the default buffer.
GLX_RGBA True if color buffers store red, green, blue, and
alpha values, False if they store color indexes.
GLX_DOUBLEBUFFER True if color buffers exist in front/back pairs that
can be swapped, False otherwise.
GLX_STEREO True if color buffers exist in left/right pairs,
False otherwise.
GLX_AUX_BUFFERS Number of auxiliary color buffers that are available.
Zero indicates that no auxiliary color buffers exist.
GLX_RED_SIZE Number of bits of red stored in each color buffer.
Undefined if GLX_RGBA is False.
GLX_GREEN_SIZE Number of bits of green stored in each color buffer.
Undefined if GLX_RGBA is False.
GLX_BLUE_SIZE Number of bits of blue stored in each color buffer.
Undefined if GLX_RGBA is False.
GLX_ALPHA_SIZE Number of bits of alpha stored in each color buffer.
Undefined if GLX_RGBA is False.
GLX_DEPTH_SIZE Number of bits in the depth buffer.
GLX_STENCIL_SIZE Number of bits in the stencil buffer.
GLX_ACCUM_RED_SIZE Number of bits of red stored in the accumulation
buffer.
GLX_ACCUM_GREEN_SIZE Number of bits of green stored in the accumulation
buffer.
GLX_ACCUM_BLUE_SIZE Number of bits of blue stored in the accumulation
buffer.
GLX_ACCUM_ALPHA_SIZE Number of bits of alpha stored in the accumulation
buffer.
The X protocol allows a single visual ID to be instantiated with different
numbers of bits per pixel. Windows or GLX pixmaps that will be rendered
with OpenGL, however, must be instantiated with a color buffer depth of
GLX_BUFFER_SIZE.
Although a GLX implementation can export many visuals that support OpenGL
rendering, it must support at least two. One is an RGBA visual with at
least one color buffer, a stencil buffer of at least 1 bit, a depth buffer
of at least 12 bits, and an accumulation buffer. Alpha bitplanes are
optional in this visual. However, its color buffer size must be as great
as that of the deepest TrueColor, DirectColor, PseudoColor, or StaticColor
visual supported on level zero, and it must itself be made available on
level zero.
The other required visual is a color index one with at least one color
buffer, a stencil buffer of at least 1 bit, and a depth buffer of at least
12 bits. This visual must have as many color bitplanes as the deepest
PseudoColor or StaticColor visual supported on level zero, and it must
itself be made available on level zero.
Applications are best written to select the visual that most closely meets
their requirements. Creating windows or GLX pixmaps with unnecessary
buffers can result in reduced rendering performance as well as poor
resource allocation.
Notes
XVisualInfo is defined in Xutil.h. It is a structure that includes visual,
visualID, screen, and depth elements.
Errors
GLX_NO_EXTENSION is returned if dpy does not support the GLX extension.
GLX_BAD_SCREEN is returned if the screen of vis does not correspond to a
screen.
GLX_BAD_ATTRIB is returned if attrib is not a valid GLX attribute.
GLX_BAD_VISUAL is returned if vis doesn't support GLX and an attribute
other than GLX_USE_GL is requested.
See Also
glXChooseVisual, glXCreateContext
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ΓòÉΓòÉΓòÉ 3.125. glXGetCurrentContext ΓòÉΓòÉΓòÉ
OpenGL man pages
glXGetCurrentContext
Name
glXGetCurrentContext - return the current context
C Specification
GLXContext glXGetCurrentContext( void )
Description
glXGetCurrentContext returns the current context, as specified by
glXMakeCurrent. If there is no current context, NULL is returned.
glXGetCurrentContext returns client-side information. It does not make a
round trip to the server.
See Also
glXCreateContext, glXMakeCurrent
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ΓòÉΓòÉΓòÉ 3.126. glXGetCurrentDrawable ΓòÉΓòÉΓòÉ
OpenGL man pages
glXGetCurrentDrawable
Name
glXGetCurrentDrawable - return the current drawable
C Specification
GLXDrawable glXGetCurrentDrawable( void )
Description
glXGetCurrentDrawable returns the current drawable, as specified by
glXMakeCurrent. If there is no current drawable, None is returned.
glXGetCurrentDrawable returns client-side information. It does not make a
round trip to the server.
See Also
glXCreateGLXPixmap, glXMakeCurrent
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ΓòÉΓòÉΓòÉ 3.127. glXIsDirect ΓòÉΓòÉΓòÉ
OpenGL man pages
glXIsDirect
Name
glXIsDirect - indicate whether direct rendering is enabled
C Specification
Bool glXIsDirect( Display *dpy,
GLXContext ctx )
Parameters
dpy Specifies the connection to the X server.
ctx Specifies the GLX context that is being queried.
Description
glXIsDirect returns True if ctx is a direct rendering context, False
otherwise. Direct rendering contexts pass rendering commands directly from
the calling process's address space to the rendering system, bypassing the
X server. Nondirect rendering contexts pass all rendering commands to the
X server.
Errors
GLXBadContext is generated if ctx is not a valid GLX context.
See Also
glXCreateContext
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ΓòÉΓòÉΓòÉ 3.128. glXMakeCurrent ΓòÉΓòÉΓòÉ
OpenGL man pages
glXMakeCurrent
Name
glXMakeCurrent - attach a GLX context to a window or a GLX pixmap
C Specification
Bool glXMakeCurrent( Display *dpy,
GLXDrawable drawable,
GLXContext ctx )
Parameters
dpy Specifies the connection to the X server.
drawable Specifies a GLX drawable. Must be either an X window ID or a GLX
pixmap ID.
ctx Specifies a GLX rendering context that is to be attached to
drawable.
Description
glXMakeCurrent does two things: It makes ctx the current GLX rendering
context of the calling thread, replacing the previously current context if
there was one, and it attaches ctx to a GLX drawable, either a window or a
GLX pixmap. As a result of these two actions, subsequent OpenGL rendering
calls use rendering context ctx to modify GLX drawable drawable. Because
glXMakeCurrent always replaces the current rendering context with ctx,
there can be only one current context per thread.
Pending commands to the previous context, if any, are flushed before it is
released.
The first time ctx is made current to any thread, its viewport is set to
the full size of drawable. Subsequent calls by any thread to
glXMakeCurrent with ctx have no effect on its viewport.
To release the current context without assigning a new one, call
glXMakeCurrent with drawable and ctx set to None and NULL respectively.
glXMakeCurrent returns True if it is successful, False otherwise. If False
is returned, the previously current rendering context and drawable (if any)
remain unchanged.
Notes
A process is a single-execution environment, implemented in a single
address space, consisting of one or more threads.
A thread is one of a set of subprocesses that share a single address space,
but maintain separate program counters, stack spaces, and other related
global data. A thread that is the only member of its subprocess group is
equivalent to a process.
Errors
BadMatch is generated if drawable was not created with the same X screen
and visual as ctx. It is also generated if drawable is None and ctx is not
None.
BadAccess is generated if ctx was current to another thread at the time
glXMakeCurrent was called.
GLXBadDrawable is generated if drawable is not a valid GLX drawable.
GLXBadContext is generated if ctx is not a valid GLX context.
GLXBadContextState is generated if glXMakeCurrent is called between a
glBegin and the corresponding call to glEnd.
GLXBadContextState is also generated if the rendering context current to
the calling thread has OpenGL renderer state GL_FEEDBACK or GL_SELECT.
GLXBadCurrentWindow is generated if there are pending OpenGL commands for
the previous context and the current drawable is a window that is no longer
valid.
BadAlloc may be generated if the server has delayed allocation of ancillary
buffers until glXMakeCurrent is called, only to find that it has
insufficient resources to complete the allocation.
See Also
glXCreateContext, glXCreateGLXPixmap
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ΓòÉΓòÉΓòÉ 3.129. glXQueryExtension ΓòÉΓòÉΓòÉ
OpenGL man pages
glXQueryExtension
Name
glXQueryExtension - indicate whether the GLX extension is supported
C Specification
Bool glXQueryExtension( Display *dpy,
int *errorBase,
int *eventBase )
Parameters
dpy Specifies the connection to the X server.
errorBase Returns the base error code of the GLX server extension.
eventBase Returns the base event code of the GLX server extension.
Description
glXQueryExtension returns True if the X server of connection dpy supports
the GLX extension, False otherwise. If True is returned, then errorBase
and eventBase return the error base and event base of the GLX extension.
Otherwise, errorBase and eventBase are unchanged.
errorBase and eventBase do not return values if they are specified as NULL.
Notes
eventBase is included for future extensions. GLX does not currently define
any events.
See Also
glXQueryVersion
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ΓòÉΓòÉΓòÉ 3.130. glXQueryVersion ΓòÉΓòÉΓòÉ
OpenGL man pages
glXQueryVersion
Name
glXQueryVersion - return the version numbers of the GLX extension
C Specification
Bool glXQueryVersion( Display *dpy,
int *major,
int *minor )
Parameters
dpy Specifies the connection to the X server.
major Returns the major version number of the GLX server extension.
minor Returns the minor version number of the GLX server extension.
Description
glXQueryVersion returns the major and minor version numbers of the GLX
extension available on the connection dpy. The client library and the
server implementations must have the same major version number or else
glXQueryVersion will return False. The minor version that is returned is
the minimum of the two minor version numbers.
major and minor do not return values if they are specified as NULL.
Errors
glXQueryVersion returns False if it fails, True otherwise. major and minor
are not updated when False is returned.
See Also
glXQueryExtension
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ΓòÉΓòÉΓòÉ 3.131. glXSwapBuffers ΓòÉΓòÉΓòÉ
OpenGL man pages
glXSwapBuffers
Name
glXSwapBuffers - make back buffer visible
C Specification
void glXSwapBuffers( Display *dpy,
GLXDrawable drawable )
Parameters
dpy Specifies the connection to the X server.
drawable Specifies the window whose buffers are to be swapped.
Description
glXSwapBuffers promotes the contents of the back buffer of drawable to
become the contents of the front buffer of drawable. The contents of the
back buffer then become undefined. The update typically takes place during
the vertical retrace of the monitor, rather than immediately after
glXSwapBuffers is called. All GLX rendering contexts share the same notion
of which are front buffers and which are back buffers.
An implicit glFlush is done by glXSwapBuffers before it returns.
Subsequent OpenGL commands can be issued immediately after calling
glXSwapBuffers, but are not executed until the buffer exchange is
completed.
If drawable was not created with respect to a double-buffered visual,
glXSwapBuffers has no effect, and no error is generated.
Notes
Synchronization of multiple GLX contexts rendering to the same double-
buffered window is the responsibility of the clients. The X
Synchronization Extension can be used to facilitate such cooperation.
Errors
GLXBadDrawable is generated if drawable is not a valid GLX drawable.
GLXBadCurrentWindow is generated if dpy and drawable are respectively the
display and drawable associated with the current context of the calling
thread, and drawable identifies a window that is no longer valid.
See Also
glFlush
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ΓòÉΓòÉΓòÉ 3.132. glXUseXFont ΓòÉΓòÉΓòÉ
OpenGL man pages
glXUseXFont
Name
glXUseXFont - create bitmap display lists from an X font
C Specification
void glXUseXFont( Font font,
int first,
int count,
int listBase )
Parameters
font Specifies the font from which character glyphs are to be taken.
first Specifies the index of the first glyph to be taken.
count Specifies the number of glyphs to be taken.
listBase Specifies the index of the first display list to be generated.
Description
glXUseXFont generates count display lists, named listBase through
listBase+count-1, each containing a single glBitmap command. The
parameters of the glBitmap command of display list listBase+i are derived
from glyph first+i. Bitmap parameters xorig, yorig, width, and height are
computed from font metrics as descent-1, -lbearing, rbearing-lbearing, and
ascent+descent, respectively. xmove is taken from the glyph's width
metric, and ymove is set to zero. Finally, the glyph's image is converted
to the appropriate format for glBitmap.
Using glXUseXFont may be more efficient than accessing the X font and
generating the display lists explicitly, both because the display lists are
created on the server without requiring a round trip of the glyph data, and
because the server may choose to delay the creation of each bitmap until it
is accessed.
Empty display lists are created for all glyphs that are requested and are
not defined in font. glXUseXFont is ignored if there is no current GLX
context.
Errors
BadFont is generated if font is not a valid font.
GLXBadContextState is generated if the current GLX context is in display-
list construction mode.
GLXBadCurrentWindow is generated if the drawable associated with the
current context of the calling thread is a window, and that window is no
longer valid.
See Also
glBitmap, glXMakeCurrent
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ΓòÉΓòÉΓòÉ 3.133. glXWaitGL ΓòÉΓòÉΓòÉ
OpenGL man pages
glXWaitGL
Name
glXWaitGL - complete GL execution prior to subsequent X calls
C Specification
void glXWaitGL( void )
Description
OpenGL rendering calls made prior to glXWaitGL are guaranteed to be
executed before X rendering calls made after glXWaitGL. Although this same
result can be achieved using glFinish, glXWaitGL does not require a round
trip to the server, and it is therefore more efficient in cases where
client and server are on separate machines.
glXWaitGL is ignored if there is no current GLX context.
Notes
glXWaitGL may or may not flush the X stream.
Errors
GLXBadCurrentWindow is generated if the drawable associated with the
current context of the calling thread is a window, and that window is no
longer valid.
See Also
glFinish, glFlush, glXWaitX, XSync
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ΓòÉΓòÉΓòÉ 3.134. glXWaitX ΓòÉΓòÉΓòÉ
OpenGL man pages
glXWaitX
Name
glXWaitX - complete X execution prior to subsequent OpenGL calls
C Specification
void glXWaitX( void )
Description
X rendering calls made prior to glXWaitX are guaranteed to be executed
before OpenGL rendering calls made after glXWaitX. Although this same
result can be achieved using XSync, glXWaitX does not require a round trip
to the server, and it is therefore more efficient in cases where client and
server are on separate machines.
glXWaitX is ignored if there is no current GLX context.
Notes
glXWaitX may or may not flush the OpenGL stream.
Errors
GLXBadCurrentWindow is generated if the drawable associated with the
current context of the calling thread is a window, and that window is no
longer valid.
See Also
glFinish, glFlush, glXWaitGL, XSync
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ΓòÉΓòÉΓòÉ 3.135. gluBeginCurve ΓòÉΓòÉΓòÉ
OpenGL man pages
gluBeginCurve
Name
gluBeginCurve, gluEndCurve - delimit a NURBS curve definition
C Specification
void gluBeginCurve( GLUnurbsObj *nobj )
void gluEndCurve( GLUnurbsObj *nobj )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
Description
Use gluBeginCurve to mark the beginning of a NURBS curve definition. After
calling gluBeginCurve, make one or more calls to gluNurbsCurve to define
the attributes of the curve. Exactly one of the calls to gluNurbsCurve
must have a curve type of GL_MAP1_VERTEX_3 or GL_MAP1_VERTEX_4. To mark
the end of the NURBS curve definition, call gluEndCurve.
OpenGL evaluators are used to render the NURBS curve as a series of line
segments. Evaluator state is preserved during rendering with
glPushAttrib(GL_EVAL_BIT) and glPopAttrib(). See the glPushAttrib reference
page for details on exactly what state these calls preserve.
Example
The following commands render a textured NURBS curve with normals; texture
coordinates and normals are also specified as NURBS curves:
gluBeginCurve(nobj);
gluNurbsCurve(nobj, ..., GL_MAP1_TEXTURE_COORD_2);
gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4); gluEndCurve(nobj);
See Also
gluBeginSurface, gluBeginTrim, gluNewNurbsRenderer, gluNurbsCurve,
glPopAttrib, glPushAttrib
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ΓòÉΓòÉΓòÉ 3.136. gluBeginPolygon ΓòÉΓòÉΓòÉ
OpenGL man pages
gluBeginPolygon (Obsolete in GLU version 1.2 and later)
Name
gluBeginPolygon, gluEndPolygon - delimit a polygon description
C Specification
void gluBeginPolygon( GLUtesselator *tess )
void gluEndPolygon( GLUtesselator *tess )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
Description
gluBeginPolygon and gluEndPolygon delimit the definition of a nonconvex
polygon. To define such a polygon, first call gluBeginPolygon. Then
define the contours of the polygon by calling gluTessVertex for each vertex
and gluNextContour to start each new contour. Finally, call gluEndPolygon
to signal the end of the definition. See the gluTessVertex and
gluNextContour reference pages for more details.
Once gluEndPolygon is called, the polygon is tessellated, and the resulting
triangles are described through callbacks. See gluTessCallback for
descriptions of the callback functions.
Notes
As of GLU version 1.2, this command is obsolete and is provided for backwards
compatibility only. GLU version 1.2 (and later) can be distinguished during
compilation by checking if the pre-processor symbol GLU_VERSION_1_2 is defined.
Calls to gluBeginPolygon are mapped to gluTessBeginPolygon followed by
gluTessBeginContour. Calls to gluEndPolygon are mapped to gluTessEndContour
followed by gluTessEndPolygon.
Example
A quadrilateral with a triangular hole in it can be described like this:
gluBeginPolygon(tobj);
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluNextContour(tobj, GLU_INTERIOR);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluEndPolygon(tobj);
See Also
gluNewTess, gluNextContour, gluTessCallback, gluTessVertex,
gluTessBeginPolygon, gluTessBeginContour
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ΓòÉΓòÉΓòÉ 3.137. gluBeginPolygon ΓòÉΓòÉΓòÉ
OpenGL man pages
gluBeginPolygon (GLU versions 1.0 and 1.1)
Name
gluBeginPolygon, gluEndPolygon - delimit a polygon description
C Specification
void gluBeginPolygon( GLUtriangulatorObj *tobj )
void gluEndPolygon( GLUtriangulatorObj *tobj )
Parameters
tobj Specifies the tessellation object (created with gluNewTess).
Description
gluBeginPolygon and gluEndPolygon delimit the definition of a nonconvex
polygon. To define such a polygon, first call gluBeginPolygon. Then
define the contours of the polygon by calling gluTessVertex for each vertex
and gluNextContour to start each new contour. Finally, call gluEndPolygon
to signal the end of the definition. See the gluTessVertex and
gluNextContour reference pages for more details.
Once gluEndPolygon is called, the polygon is tessellated, and the resulting
triangles are described through callbacks. See gluTessCallback for
descriptions of the callback functions.
Example
A quadrilateral with a triangular hole in it can be described like this:
gluBeginPolygon(tobj);
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluNextContour(tobj, GLU_INTERIOR);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluEndPolygon(tobj);
See Also
gluNewTess, gluNextContour, gluTessCallback, gluTessVertex
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ΓòÉΓòÉΓòÉ 3.138. gluBeginSurface ΓòÉΓòÉΓòÉ
OpenGL man pages
gluBeginSurface
Name
gluBeginSurface, gluEndSurface - delimit a NURBS surface definition
C Specification
void gluBeginSurface( GLUnurbsObj *nobj )
void gluEndSurface( GLUnurbsObj *nobj )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
Description
Use gluBeginSurface to mark the beginning of a NURBS surface definition.
After calling gluBeginSurface, make one or more calls to gluNurbsSurface to
define the attributes of the surface. Exactly one of these calls to
gluNurbsSurface must have a surface type of GL_MAP2_VERTEX_3 or
GL_MAP2_VERTEX_4. To mark the end of the NURBS surface definition, call
gluEndSurface.
Trimming of NURBS surfaces is supported with gluBeginTrim, gluPwlCurve,
gluNurbsCurve, and gluEndTrim. Refer to the gluBeginTrim reference page
for details.
OpenGL evaluators are used to render the NURBS surface as a set of
polygons. Evaluator state is preserved during rendering with
glPushAttrib(GL_EVAL_BIT) and glPopAttrib(). See the glPushAttrib reference
page for details on exactly what state these calls preserve.
Example
The following commands render a textured NURBS surface with normals; the
texture coordinates and normals are also described as NURBS surfaces:
gluBeginSurface(nobj);
gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2);
gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL);
gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4); gluEndSurface(nobj);
See Also
gluBeginCurve, gluBeginTrim, gluNewNurbsRenderer, gluNurbsCurve,
gluNurbsSurface, gluPwlCurve
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ΓòÉΓòÉΓòÉ 3.139. gluBeginTrim ΓòÉΓòÉΓòÉ
OpenGL man pages
gluBeginTrim
Name
gluBeginTrim, gluEndTrim - delimit a NURBS trimming loop definition
C Specification
void gluBeginTrim( GLUnurbsObj *nobj )
void gluEndTrim( GLUnurbsObj *nobj )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
Description
Use gluBeginTrim to mark the beginning of a trimming loop, and gluEndTrim
to mark the end of a trimming loop. A trimming loop is a set of oriented
curve segments (forming a closed curve) that define boundaries of a NURBS
surface. You include these trimming loops in the definition of a NURBS
surface, between calls to gluBeginSurface and gluEndSurface.
The definition for a NURBS surface can contain many trimming loops. For
example, if you wrote a definition for a NURBS surface that resembled a
rectangle with a hole punched out, the definition would contain two
trimming loops. One loop would define the outer edge of the rectangle;
the other would define the hole punched out of the rectangle. The
definitions of each of these trimming loops would be bracketed by a
gluBeginTrim/gluEndTrim pair.
The definition of a single closed trimming loop can consist of multiple
curve segments, each described as a piecewise linear curve (see
gluPwlCurve) or as a single NURBS curve (see gluNurbsCurve), or as a
combination of both in any order. The only library calls that can appear
in a trimming loop definition (between the calls to gluBeginTrim and
gluEndTrim) are gluPwlCurve and gluNurbsCurve.
The area of the NURBS surface that is displayed is the region in the domain
to the left of the trimming curve as the curve parameter increases. Thus,
the retained region of the NURBS surface is inside a counterclockwise
trimming loop and outside a clockwise trimming loop. For the rectangle
mentioned earlier, the trimming loop for the outer edge of the rectangle
runs counterclockwise, while the trimming loop for the punched-out hole
runs clockwise.
If you use more than one curve to define a single trimming loop, the curve
segments must form a closed loop (that is, the endpoint of each curve must
be the starting point of the next curve, and the endpoint of the final
curve must be the starting point of the first curve). If the endpoints of
the curve are sufficiently close together but not exactly coincident, they
will be coerced to match. If the endpoints are not sufficiently close, an
error results (see gluNurbsCallback).
If a trimming loop definition contains multiple curves, the direction of
the curves must be consistent (that is, the inside must be to the left of
all of the curves). Nested trimming loops are legal as long as the curve
orientations alternate correctly. Trimming curves cannot be self-
intersecting, nor can they intersect one another (or an error results).
If no trimming information is given for a NURBS surface, the entire surface
is drawn.
Example
This code fragment defines a trimming loop that consists of one piecewise
linear curve, and two NURBS curves:
gluBeginTrim(nobj);
gluPwlCurve(..., GLU_MAP1_TRIM_2);
gluNurbsCurve(..., GLU_MAP1_TRIM_2);
gluNurbsCurve(..., GLU_MAP1_TRIM_3); gluEndTrim(nobj);
See Also
gluBeginSurface, gluNewNurbsRenderer, gluNurbsCallback, gluNurbsCurve,
gluPwlCurve
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ΓòÉΓòÉΓòÉ 3.140. gluBuild1DMipmaps ΓòÉΓòÉΓòÉ
OpenGL man pages
gluBuild1DMipmaps
Name
gluBuild1DMipmaps - create 1-D mipmaps
C Specification
int gluBuild1DMipmaps( GLenum target,
GLint components,
GLint width,
GLenum format,
GLenum type,
const void *data )
Parameters
target Specifies the target texture. Must be GL_TEXTURE_1D.
components Specifies the number of color components in the texture. Must
be 1, 2, 3, or 4.
width Specifies the width of the texture image.
format Specifies the format of the pixel data. Must be one of
GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB,
GL_RGBA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
type Specifies the data type for data. Must be one of
GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,
GL_SHORT, GL_UNSIGNED_INT, GL_INT, or GL_FLOAT.
data Specifies a pointer to the image data in memory.
Description
gluBuild1DMipmaps obtains the input image and generates all mipmap images
(using gluScaleImage) so that the input image can be used as a mipmapped
texture image. glTexImage1D is then called to load each of the images. If
the width of the input image is not a power of two, then the image is
scaled to the nearest power of two before the mipmaps are generated.
A return value of zero indicates success. Otherwise, a GLU error code is
returned (see gluErrorString).
Please refer to the glTexImage1D reference page for a description of the
acceptable values for the format parameter. See the glDrawPixels reference
page for a description of the acceptable values for the type parameter.
See Also
glTexImage1D, gluBuild2DMipmaps, gluErrorString, gluScaleImage
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ΓòÉΓòÉΓòÉ 3.141. gluBuild2DMipmaps ΓòÉΓòÉΓòÉ
OpenGL man pages
gluBuild2DMipmaps
Name
gluBuild2DMipmaps - create 2-D mipmaps
C Specification
int gluBuild2DMipmaps( GLenum target,
GLint components,
GLint width,
GLint height,
GLenum format,
GLenum type,
const void *data )
Parameters
target Specifies the target texture. Must be GL_TEXTURE_2D.
components Specifies the number of color components in the texture. Must
be 1, 2, 3, or 4.
width, height
Specifies the width and height, respectively, of the texture
image.
format Specifies the format of the pixel data. Must be one of:
GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB,
GL_RGBA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
type Specifies the data type for data. Must be one of:
GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,
GL_SHORT, GL_UNSIGNED_INT, GL_INT, or GL_FLOAT.
data Specifies a pointer to the image data in memory.
Description
gluBuild2DMipmaps obtains the input image and generates all mipmap images
(using gluScaleImage) so that the input image can be used as a mipmapped
texture image. glTexImage2D is then called to load each of the images. If
the dimensions of the input image are not powers of two, then the image is
scaled so that both the width and height are powers of two before the
mipmaps are generated.
A return value of 0 indicates success. Otherwise, a GLU error code is
returned (see gluErrorString).
Please refer to the glTexImage1D reference page for a description of the
acceptable values for the format parameter. See the glDrawPixels reference
page for a description of the acceptable values for the type parameter.
See Also
glDrawPixels, glTexImage1D, glTexImage2D, gluBuild1DMipmaps,
gluErrorString, gluScaleImage
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.142. gluCylinder ΓòÉΓòÉΓòÉ
OpenGL man pages
gluCylinder
Name
gluCylinder - draw a cylinder
C Specification
void gluCylinder( GLUquadricObj *qobj,
GLdouble baseRadius,
GLdouble topRadius,
GLdouble height,
GLint slices,
GLint stacks )
Parameters
qobj Specifies the quadrics object (created with gluNewQuadric).
baseRadius Specifies the radius of the cylinder at z = 0.
topRadius Specifies the radius of the cylinder at z = height.
height Specifies the height of the cylinder.
slices Specifies the number of subdivisions around the z axis.
stacks Specifies the number of subdivisions along the z axis.
Description
gluCylinder draws a cylinder oriented along the z axis. The base of the
cylinder is placed at z = 0, and the top at z=height. Like a sphere, a
cylinder is subdivided around the z axis into slices, and along the z axis
into stacks.
Note that if topRadius is set to zero, then this routine will generate a
cone.
If the orientation is set to GLU_OUTSIDE (with gluQuadricOrientation), then
any generated normals point away from the z axis. Otherwise, they point
toward the z axis.
If texturing is turned on (with gluQuadricTexture), then texture
coordinates are generated so that t ranges linearly from 0.0 at z = 0 to
1.0 at z = height, and s ranges from 0.0 at the +y axis, to 0.25 at the +x
axis, to 0.5 at the -y axis, to 0.75 at the -x axis, and back to 1.0 at the
+y axis.
See Also
gluDisk, gluNewQuadric, gluPartialDisk, gluQuadricTexture, gluSphere
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ΓòÉΓòÉΓòÉ 3.143. gluDeleteNurbsRenderer ΓòÉΓòÉΓòÉ
OpenGL man pages
gluDeleteNurbsRenderer
Name
gluDeleteNurbsRenderer - destroy a NURBS object
C Specification
void gluDeleteNurbsRenderer( GLUnurbsObj *nobj )
Parameters
nobj Specifies the NURBS object to be destroyed (created with
gluNewNurbsRenderer).
Description
gluDeleteNurbsRenderer destroys the NURBS object and frees any memory used
by it. Once gluDeleteNurbsRenderer has been called, nobj cannot be used
again.
See Also
gluNewNurbsRenderer
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ΓòÉΓòÉΓòÉ 3.144. gluDeleteQuadric ΓòÉΓòÉΓòÉ
OpenGL man pages
gluDeleteQuadric
Name
gluDeleteQuadric - destroy a quadrics object
C Specification
void gluDeleteQuadric( GLUquadricObj *state )
Parameters
state Specifies the quadrics object to be destroyed (created with
gluNewQuadric).
Description
gluDeleteQuadric destroys the quadrics object and frees any memory used by
it. Once gluDeleteQuadric has been called, state cannot be used again.
See Also
gluNewQuadric
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.145. gluDeleteTess ΓòÉΓòÉΓòÉ
OpenGL man pages
gluDeleteTess (GLU version 1.2 and later)
Name
gluDeleteTess - destroy a tessellation object
C Specification
void gluDeleteTess( GLUtesselator *tess )
Parameters
tess Specifies the tessellation object to destroy (created with
gluNewTess).
Description
gluDeleteTess destroys the indicated tessellation object and frees any
memory that it used.
See Also
gluBeginPolygon, gluNewTess, gluTessCallback
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.146. gluDeleteTess ΓòÉΓòÉΓòÉ
OpenGL man pages
gluDeleteTess (GLU version 1.0 and 1.1)
Name
gluDeleteTess - destroy a tessellation object
C Specification
void gluDeleteTess( GLUtriangulatorObj *tobj )
Parameters
tobj Specifies the tessellation object to destroy (created with
gluNewTess).
Description
gluDeleteTess destroys the indicated tessellation object and frees any
memory that it used.
See Also
gluBeginPolygon, gluNewTess, gluTessCallback
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.147. gluDisk ΓòÉΓòÉΓòÉ
OpenGL man pages
gluDisk
Name
gluDisk - draw a disk
C Specification
void gluDisk( GLUquadricObj *qobj,
GLdouble innerRadius,
GLdouble outerRadius,
GLint slices,
GLint loops )
Parameters
qobj Specifies the quadrics object (created with gluNewQuadric).
innerRadius Specifies the inner radius of the disk (may be 0).
outerRadius Specifies the outer radius of the disk.
slices Specifies the number of subdivisions around the z axis.
loops Specifies the number of concentric rings about the origin into
which the disk is subdivided.
Description
gluDisk renders a disk on the z = 0 plane. The disk has a radius of
outerRadius, and contains a concentric circular hole with a radius of
innerRadius. If innerRadius is 0, then no hole is generated. The disk is
subdivided around the z axis into slices (like pizza slices), and also
about the z axis into rings (as specified by slices and loops,
respectively).
With respect to orientation, the +z side of the disk is considered to be
"outside" (see gluQuadricOrientation). This means that if the orientation
is set to GLU_OUTSIDE, then any normals generated point along the +z axis.
Otherwise, they point along the -z axis.
If texturing is turned on (with gluQuadricTexture), texture coordinates are
generated linearly such that where r=outerRadius, the value at (r, 0, 0) is
(1, 0.5), at (0, r, 0) it is (0.5, 1), at (-r, 0, 0) it is (0, 0.5), and at
(0, -r, 0) it is (0.5, 0).
See Also
gluCylinder, gluNewQuadric, gluPartialDisk, gluQuadricOrientation,
gluQuadricTexture, gluSphere
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ΓòÉΓòÉΓòÉ 3.148. gluErrorString ΓòÉΓòÉΓòÉ
OpenGL man pages
gluErrorString
Name
gluErrorString - produce an error string from an OpenGL or GLU error code
C Specification
const GLubyte* gluErrorString( GLenum errorCode )
Parameters
errorCode Specifies an OpenGL or GLU error code.
Description
gluErrorString produces an error string from an OpenGL or GLU error code.
The string is in an ISO Latin 1 format. For example,
gluErrorString(GL_OUT_OF_MEMORY) returns the string out of memory.
The standard GLU error codes are GLU_INVALID_ENUM, GLU_INVALID_VALUE, and
GLU_OUT_OF_MEMORY. Certain other GLU functions can return specialized
error codes through callbacks. Refer to the glGetError reference page for
the list of OpenGL error codes.
See Also
glGetError, gluNurbsCallback, gluQuadricCallback, gluTessCallback
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ΓòÉΓòÉΓòÉ 3.149. gluGetNurbsProperty ΓòÉΓòÉΓòÉ
OpenGL man pages
gluGetNurbsProperty
Name
gluGetNurbsProperty - get a NURBS property
C Specification
void gluGetNurbsProperty( GLUnurbsObj *nobj,
GLenum property,
GLfloat *value )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
property Specifies the property whose value is to be fetched. Valid
values are GLU_CULLING, GLU_SAMPLING_TOLERANCE, GLU_DISPLAY_MODE,
GLU_AUTO_LOAD_MATRIX, GLU_PARAMETRIC_TOLERANCE,
GLU_SAMPLING_METHOD, GLU_U_STEP, and GLU_V_STEP.
value Specifies a pointer to the location into which the value of the
named property is written.
Description
gluGetNurbsProperty is used to retrieve properties stored in a NURBS
object. These properties affect the way that NURBS curves and surfaces are
rendered. Please refer to the gluNurbsProperty reference page for
information about what the properties are and what they do.
See Also
gluNewNurbsRenderer, gluNurbsProperty
Notes
GLU_PARAMETRIC_TOLERANCE, GLU_SAMPLING_METHOD, GLU_U_STEP, and GLU_V_STEP are
additions to GLU starting with GLU version 1.1. This version can be distinguished
during compilation by checking if the pre-processor symbol GLU_VERSION_1_1 is
defined.
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ΓòÉΓòÉΓòÉ 3.150. gluGetTessProperty ΓòÉΓòÉΓòÉ
OpenGL man pages
gluGetTessProperty (GLU version 1.2 and later)
Name
gluGetTessProperty - get a tessellation object property
C Specification
void gluGetTessProperty( GLUtesselator *tess,
GLenum which,
GLdouble *value )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
which Specifies the property whose value is to be fetched. Valid values
are GLU_TESS_WINDING_RULE, GLU_TESS_BOUNDARY_ONLY, and
GLU_TESS_TOLERANCE.
value Specifies a pointer to the location into which the value of the
named property is written.
Description
gluGetTessProperty is used to retrieve properties stored in a tessellation
object. These properties affect the way that tessellation objects are
interpreted and rendered. Please refer to the gluTessProperty reference
page for information about what the properties are and what they do.
See Also
gluNewTess, gluTessProperty
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ΓòÉΓòÉΓòÉ 3.151. gluLoadSamplingMatrices ΓòÉΓòÉΓòÉ
OpenGL man pages
gluLoadSamplingMatrices
Name
gluLoadSamplingMatrices - load NURBS sampling and culling matrices
C Specification
void gluLoadSamplingMatrices( GLUnurbsObj *nobj,
const GLfloat modelMatrix[16],
const GLfloat projMatrix[16],
const GLint viewport[4]); )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
modelMatrix Specifies a modelview matrix (as from a glGetFloatv call).
projMatrix Specifies a projection matrix (as from a glGetFloatv call).
viewport; Specifies a viewport (as from a glGetIntegerv call).
Description
gluLoadSamplingMatrices uses modelMatrix, projMatrix, and viewport; to
recompute the sampling and culling matrices stored in nobj. The sampling
matrix determines how finely a NURBS curve or surface must be tessellated
to satisfy the sampling tolerance (as determined by the
GLU_SAMPLING_TOLERANCE property). The culling matrix is used in deciding
if a NURBS curve or surface should be culled before rendering (when the
GLU_CULLING property is turned on).
gluLoadSamplingMatrices is necessary only if the GLU_AUTO_LOAD_MATRIX
property is turned off (see gluNurbsProperty). Although it can be
convenient to leave the GLU_AUTO_LOAD_MATRIX property turned on, there can
be a performance penalty for doing so. (A round trip to the OpenGL server
is needed to fetch the current values of the modelview matrix, projection
matrix, and viewport.)
See Also
gluGetNurbsProperty, gluNewNurbsRenderer, gluNurbsProperty
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ΓòÉΓòÉΓòÉ 3.152. gluLookAt ΓòÉΓòÉΓòÉ
OpenGL man pages
gluLookAt
Name
gluLookAt - define a viewing transformation
C Specification
void gluLookAt( GLdouble eyex,
GLdouble eyey,
GLdouble eyez,
GLdouble centerx,
GLdouble centery,
GLdouble centerz,
GLdouble upx,
GLdouble upy,
GLdouble upz )
Parameters
eyex, eyey, eyez
Specifies the position of the eye point.
centerx, centery, centerz
Specifies the position of the reference point.
upx, upy, upz Specifies the direction of the up vector.
Description
gluLookAt creates a viewing matrix derived from an eye point, a reference
point indicating the center of the scene, and an up vector. The matrix
maps the reference point to the negative z axis and the eye point to the
origin, so that, when a typical projection matrix is used, the center of
the scene maps to the center of the viewport. Similarly, the direction
described by the up vector projected onto the viewing plane is mapped to
the positive y axis so that it points upward in the viewport. The up
vector must not be parallel to the line of sight from the eye to the
reference point.
The matrix generated by gluLookAt postmultiplies the current matrix.
See Also
glFrustum, gluPerspective
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ΓòÉΓòÉΓòÉ 3.153. gluNewNurbsRenderer ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNewNurbsRenderer
Name
gluNewNurbsRenderer - create a NURBS object
C Specification
GLUnurbsObj* gluNewNurbsRenderer( void )
Description
gluNewNurbsRenderer creates and returns a pointer to a new NURBS object.
This object must be referred to when calling NURBS rendering and control
functions. A return value of zero means that there is not enough memory to
allocate the object.
See Also
gluBeginCurve, gluBeginSurface, gluBeginTrim, gluDeleteNurbsRenderer,
gluNurbsCallback, gluNurbsProperty
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ΓòÉΓòÉΓòÉ 3.154. gluNewQuadric ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNewQuadric
Name
gluNewQuadric - create a quadrics object
C Specification
GLUquadricObj* gluNewQuadric( void )
Description
gluNewQuadric creates and returns a pointer to a new quadrics object. This
object must be referred to when calling quadrics rendering and control
functions. A return value of zero means that there is not enough memory to
allocate the object.
See Also
gluCylinder, gluDeleteQuadric, gluDisk, gluPartialDisk, gluQuadricCallback,
gluQuadricDrawStyle, gluQuadricNormals, gluQuadricOrientation,
gluQuadricTexture, gluSphere
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ΓòÉΓòÉΓòÉ 3.155. gluNewTess ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNewTess (GLU version 1.2 and later)
Name
gluNewTess - create a tessellation object
C Specification
GLUtesselator* gluNewTess( void )
Description
gluNewTess creates and returns a pointer to a new tessellation object.
This object must be referred to when calling tessellation functions. A
return value of zero means that there is not enough memory to allocate the
object.
See Also
gluTessBeginPolygon, gluDeleteTess, gluTessCallback
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ΓòÉΓòÉΓòÉ 3.156. gluNewTess ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNewTess (GLU versions 1.0 and 1.1)
Name
gluNewTess - create a tessellation object
C Specification
GLUtriangulatorObj* gluNewTess( void )
Description
gluNewTess creates and returns a pointer to a new tessellation object.
This object must be referred to when calling tessellation functions. A
return value of zero means that there is not enough memory to allocate the
object.
See Also
gluBeginPolygon, gluDeleteTess, gluTessCallback
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ΓòÉΓòÉΓòÉ 3.157. gluNextContour ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNextContour (Obsolete in GLU version 1.2 and later)
Name
gluNextContour - mark the beginning of another contour
C Specification
void gluNextContour( GLUtesselator *tess,
GLenum type )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
type Specifies the type of the contour being defined. Valid values are
GLU_EXTERIOR, GLU_INTERIOR, GLU_UNKNOWN, GLU_CCW, and GLU_CW.
Description
gluNextContour is used in describing polygons with multiple contours.
After the first contour has been described through a series of
gluTessVertex calls, a gluNextContour call indicates that the previous
contour is complete and that the next contour is about to begin. Another
series of gluTessVertex calls is then used to describe the new contour.
This process can be repeated until all contours have been described.
type defines what type of contour follows. The legal contour types are as
follows:
GLU_EXTERIOR An exterior contour defines an exterior boundary of the
polygon.
GLU_INTERIOR An interior contour defines an interior boundary of the
polygon (such as a hole).
GLU_UNKNOWN An unknown contour is analyzed by the library to determine
if it is interior or exterior.
GLU_CCW, GLU_CW
The first GLU_CCW or GLU_CW contour defined is considered to
be exterior. All other contours are considered to be
exterior if they are oriented in the same direction
(clockwise or counterclockwise) as the first contour, and
interior if they are not.
If one contour is of type GLU_CCW or GLU_CW, then all
contours must be of the same type (if they are not, then all
GLU_CCW and GLU_CW contours will be changed to GLU_UNKNOWN).
Note that there is no real difference between the GLU_CCW
and GLU_CW contour types.
gluNextContour can be called before the first contour is described to
define the type of the first contour. If gluNextContour is not called
before the first contour, then the first contour is marked GLU_EXTERIOR.
Notes
As of GLU version 1.2, this command is obsolete and is provided for backwards
compatibility only. GLU version 1.2 (and later) can be distinguished during
compilation by checking if the pre-processor symbol GLU_VERSION_1_2 is defined.
Calls to gluNextContour are mapped to gluTessEndContour followed by
gluTessBeginContour.
Example
A quadrilateral with a triangular hole in it can be described as follows:
gluBeginPolygon(tobj);
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluNextContour(tobj, GLU_INTERIOR);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluEndPolygon(tobj);
See Also
gluBeginPolygon, gluNewTess, gluTessCallback, gluTessVertex,
gluTessBeginContour
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ΓòÉΓòÉΓòÉ 3.158. gluNextContour ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNextContour (GLU versions 1.0 and 1.1)
Name
gluNextContour - mark the beginning of another contour
C Specification
void gluNextContour( GLUtriangulatorObj *tobj,
GLenum type )
Parameters
tobj Specifies the tessellation object (created with gluNewTess).
type Specifies the type of the contour being defined. Valid values are
GLU_EXTERIOR, GLU_INTERIOR, GLU_UNKNOWN, GLU_CCW, and GLU_CW.
Description
gluNextContour is used in describing polygons with multiple contours.
After the first contour has been described through a series of
gluTessVertex calls, a gluNextContour call indicates that the previous
contour is complete and that the next contour is about to begin. Another
series of gluTessVertex calls is then used to describe the new contour.
This process can be repeated until all contours have been described.
type defines what type of contour follows. The legal contour types are as
follows:
GLU_EXTERIOR An exterior contour defines an exterior boundary of the
polygon.
GLU_INTERIOR An interior contour defines an interior boundary of the
polygon (such as a hole).
GLU_UNKNOWN An unknown contour is analyzed by the library to determine
if it is interior or exterior.
GLU_CCW, GLU_CW
The first GLU_CCW or GLU_CW contour defined is considered to
be exterior. All other contours are considered to be
exterior if they are oriented in the same direction
(clockwise or counterclockwise) as the first contour, and
interior if they are not.
If one contour is of type GLU_CCW or GLU_CW, then all
contours must be of the same type (if they are not, then all
GLU_CCW and GLU_CW contours will be changed to GLU_UNKNOWN).
Note that there is no real difference between the GLU_CCW
and GLU_CW contour types.
gluNextContour can be called before the first contour is described to
define the type of the first contour. If gluNextContour is not called
before the first contour, then the first contour is marked GLU_EXTERIOR.
Example
A quadrilateral with a triangular hole in it can be described as follows:
gluBeginPolygon(tobj);
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluNextContour(tobj, GLU_INTERIOR);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluEndPolygon(tobj);
See Also
gluBeginPolygon, gluNewTess, gluTessCallback, gluTessVertex
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ΓòÉΓòÉΓòÉ 3.159. gluNurbsCallback ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNurbsCallback
Name
gluNurbsCallback - define a callback for a NURBS object
C Specification
void gluNurbsCallback( GLUnurbsObj *nobj,
GLenum which,
void (*fn)( )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
which Specifies the callback being defined. The only valid value is
GLU_ERROR.
fn Specifies the function that the callback calls.
Description
gluNurbsCallback is used to define a callback to be used by a NURBS object.
If the specified callback is already defined, then it is replaced. If fn
is NULL, then any existing callback is erased.
The one legal callback is GLU_ERROR:
GLU_ERROR The error function is called when an error is encountered.
Its single argument is of type GLenum, and it indicates the
specific error that occurred. There are 37 errors unique to
NURBS named GLU_NURBS_ERROR1 through GLU_NURBS_ERROR37.
Character strings describing these errors can be retrieved
with gluErrorString.
See Also
gluErrorString, gluNewNurbsRenderer
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ΓòÉΓòÉΓòÉ 3.160. gluNurbsCurve ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNurbsCurve
Name
gluNurbsCurve - define the shape of a NURBS curve
C Specification
void gluNurbsCurve( GLUnurbsObj *nobj,
GLint nknots,
GLfloat *knot,
GLint stride,
GLfloat *ctlarray,
GLint order,
GLenum type )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
nknots Specifies the number of knots in knot. nknots equals the number
of control points plus the order.
knot Specifies an array of nknots nondecreasing knot values.
stride Specifies the offset (as a number of single-precision floating-
point values) between successive curve control points.
ctlarray Specifies a pointer to an array of control points. The
coordinates must agree with type, specified below.
order Specifies the order of the NURBS curve. order equals degree + 1,
hence a cubic curve has an order of 4.
type Specifies the type of the curve. If this curve is defined within
a gluBeginCurve/gluEndCurve pair, then the type can be any of the
valid one-dimensional evaluator types (such as GL_MAP1_VERTEX_3
or GL_MAP1_COLOR_4). Between a gluBeginTrim/gluEndTrim pair, the
only valid types are GLU_MAP1_TRIM_2 and GLU_MAP1_TRIM_3.
Description
Use gluNurbsCurve to describe a NURBS curve.
When gluNurbsCurve appears between a gluBeginCurve/gluEndCurve pair, it is
used to describe a curve to be rendered. Positional, texture, and color
coordinates are associated by presenting each as a separate gluNurbsCurve
between a gluBeginCurve/gluEndCurve pair. No more than one call to
gluNurbsCurve for each of color, position, and texture data can be made
within a single gluBeginCurve/gluEndCurve pair. Exactly one call must be
made to describe the position of the curve (a type of GL_MAP1_VERTEX_3 or
GL_MAP1_VERTEX_4).
When gluNurbsCurve appears between a gluBeginTrim/gluEndTrim pair, it is
used to describe a trimming curve on a NURBS surface. If type is
GLU_MAP1_TRIM_2, then it describes a curve in two-dimensional (u and v)
parameter space. If it is GLU_MAP1_TRIM_3, then it describes a curve in
two-dimensional homogeneous (u, v, and w) parameter space. See the
gluBeginTrim reference page for more discussion about trimming curves.
Example
The following commands render a textured NURBS curve with normals:
gluBeginCurve(nobj);
gluNurbsCurve(nobj, ..., GL_MAP1_TEXTURE_COORD_2);
gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4); gluEndCurve(nobj);
Notes
To define trim curves which stitch well use gluPwlCurve.
See Also
gluBeginCurve, gluBeginTrim, gluNewNurbsRenderer, gluPwlCurve
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ΓòÉΓòÉΓòÉ 3.161. gluNurbsProperty ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNurbsProperty
Name
gluNurbsProperty - set a NURBS property
C Specification
void gluNurbsProperty( GLUnurbsObj *nobj,
GLenum property,
GLfloat value )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
property Specifies the property to be set. Valid values are
GLU_SAMPLING_TOLERANCE, GLU_DISPLAY_MODE, GLU_CULLING,
GLU_AUTO_LOAD_MATRIX, GLU_PARAMETRIC_TOLERANCE,
GLU_SAMPLING_METHOD, GLU_U_STEP, or GLU_V_STEP.
value Specifies the value of the indicated property. It may be a
numeric value, or one of GLU_PATH_LENGTH, GLU_PARAMETRIC_ERROR,
or GLU_DOMAIN_DISTANCE.
Description
gluNurbsProperty is used to control properties stored in a NURBS object.
These properties affect the way that a NURBS curve is rendered. The legal
values for property are as follows:
GLU_SAMPLING_METHOD specifies how a NURBS surface should be
tessellated. value may be set to one of
GLU_PATH_LENGTH, GLU_PARAMETRIC_ERROR, or
GLU_DOMAIN_DISTANCE. When set to GLU_PATH_LENGTH,
the surface is rendered so that the maximum
length, in pixels, of the edges of the
tessellation polygons is no greater than what is
specified by GLU_SAMPLING_TOLERANCE.
GLU_PARAMETRIC_ERROR specifies that the surface is
rendered in such a way that the value specified by
GLU_PARAMETRIC_TOLERANCE describes the maximum
distance, in pixels, between the tessellation
polygons and the surfaces they approximate.
GLU_DOMAIN_DISTANCE allows users to specify, in
parametric coordinates, how many sample points per
unit length are taken in u, v direction. The
default value of GLU_SAMPLING_METHOD is
GLU_PATH_LENGTH.
GLU_SAMPLING_TOLERANCE specifies the maximum length, in pixels to use
when the sampling method is set to
GLU_PATH_LENGTH. The NURBS code is conservative
when rendering a curve or surface, so the actual
length can be somewhat shorter. The default value
is 50.0 pixels.
GLU_PARAMETRIC_TOLERANCE specifies the maximum distance, in pixels, to use
when the sampling method is set to
GLU_PARAMETRIC_ERROR. The default value for
GLU_PARAMETRIC_TOLERANCE is 0.5.
GLU_U_STEP specifies the number of sample points per unit
length taken along the u axis in parametric
coordinates. It is needed when GLU_SAMPLING_METHOD
is set to GLU_DOMAIN_DISTANCE. The default value
is 100.
GLU_V_STEP specifies the number of sample points per unit
length taken along the v axis in parametric
coordinate. It is needed when GLU_SAMPLING_METHOD
is set to GLU_DOMAIN_DISTANCE. The default value
is 100.
GLU_DISPLAY_MODE value defines how a NURBS surface should be
rendered. value can be set to GLU_FILL,
GLU_OUTLINE_POLYGON, or GLU_OUTLINE_PATCH. When
set to GLU_FILL, the surface is rendered as a set
of polygons. GLU_OUTLINE_POLYGON instructs the
NURBS library to draw only the outlines of the
polygons created by tessellation.
GLU_OUTLINE_PATCH causes just the outlines of
patches and trim curves defined by the user to be
drawn. The default value is GLU_FILL.
GLU_CULLING value is a Boolean value that, when set to
GL_TRUE, indicates that a NURBS curve should be
discarded prior to tessellation if its control
points lie outside the current viewport. The
default is GL_FALSE (because a NURBS curve cannot
fall entirely within the convex hull of its
control points).
GLU_AUTO_LOAD_MATRIX value is a Boolean value. When set to GL_TRUE,
the NURBS code downloads the projection matrix,
the modelview matrix, and the viewport from the
OpenGL server to compute sampling and culling
matrices for each NURBS curve that is rendered.
Sampling and culling matrices are required to
determine the tesselation of a NURBS surface into
line segments or polygons and to cull a NURBS
surface if it lies outside of the viewport. If
this mode is set to GL_FALSE, then the user needs
to provide a projection matrix, a modelview
matrix, and a viewport for the NURBS renderer to
use to construct sampling and culling matrices.
This can be done with the gluLoadSamplingMatrices
function. The default for this mode is GL_TRUE.
Changing this mode from GL_TRUE to GL_FALSE does
not affect the sampling and culling matrices until
gluLoadSamplingMatrices is called.
Notes
A property of GLU_PARAMETRIC_TOLERANCE, GLU_SAMPLING_METHOD, GLU_U_STEP, or
GLU_V_STEP, or a value of GLU_PATH_LENGTH, GLU_PARAMETRIC_ERROR,
GLU_DOMAIN_DISTANCE will only be supported in GLU version number 1.1. They
are not valid parameters in GLU 1.0.
gluGetString can be used to determine the GLU version.
See Also
gluGetNurbsProperty, gluLoadSamplingMatrices, gluNewNurbsRenderer, gluGetString.
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ΓòÉΓòÉΓòÉ 3.162. gluNurbsSurface ΓòÉΓòÉΓòÉ
OpenGL man pages
gluNurbsSurface
Name
gluNurbsSurface - define the shape of a NURBS surface
C Specification
void gluNurbsSurface( GLUnurbsObj *nobj,
GLint uknot_count,
GLfloat *uknot,
GLint vknot_count,
GLfloat *vknot,
GLint u_stride,
GLint v_stride,
GLfloat *ctlarray,
GLint uorder,
GLint vorder,
GLenum type )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
uknot_count Specifies the number of knots in the parametric u direction.
uknot Specifies an array of uknot_count nondecreasing knot values in
the parametric u direction.
vknot_count Specifies the number of knots in the parametric v direction.
vknot Specifies an array of vknot_count nondecreasing knot values in
the parametric v direction.
u_stride Specifies the offset (as a number of single-precision
floating point values) between successive control points in
the parametric u direction in ctlarray.
v_stride Specifies the offset (in single-precision floating-point
values) between successive control points in the parametric v
direction in ctlarray.
ctlarray Specifies an array containing control points for the NURBS
surface. The offsets between successive control points in the
parametric u and v directions are given by u_stride and
v_stride.
uorder Specifies the order of the NURBS surface in the parametric u
direction. The order is one more than the degree, hence a
surface that is cubic in u has a u order of 4.
vorder Specifies the order of the NURBS surface in the parametric v
direction. The order is one more than the degree, hence a
surface that is cubic in v has a v order of 4.
type Specifies type of the surface. type can be any of the valid
two-dimensional evaluator types (such as GL_MAP2_VERTEX_3 or
GL_MAP2_COLOR_4).
Description
Use gluNurbsSurface within a NURBS (Non-Uniform Rational B-Spline) surface
definition to describe the shape of a NURBS surface (before any trimming).
To mark the beginning of a NURBS surface definition, use the
gluBeginSurface command. To mark the end of a NURBS surface definition,
use the gluEndSurface command. Call gluNurbsSurface within a NURBS surface
definition only.
Positional, texture, and color coordinates are associated with a surface by
presenting each as a separate gluNurbsSurface between a
gluBeginSurface/gluEndSurface pair. No more than one call to
gluNurbsSurface for each of color, position, and texture data can be made
within a single gluBeginSurface/gluEndSurface pair. Exactly one call must
be made to describe the position of the surface (a type of GL_MAP2_VERTEX_3
or GL_MAP2_VERTEX_4).
A NURBS surface can be trimmed by using the commands gluNurbsCurve and
gluPwlCurve between calls to gluBeginTrim and gluEndTrim.
Note that a gluNurbsSurface with uknot_count knots in the u direction and
vknot_count knots in the v direction with orders uorder and vorder must
have (uknot_count - uorder) x (vknot_count - vorder) control points.
Example
The following commands render a textured NURBS surface with normals; the
texture coordinates and normals are also NURBS surfaces:
gluBeginSurface(nobj);
gluNurbsSurface(nobj, ..., GL_MAP2_TEXTURE_COORD_2);
gluNurbsSurface(nobj, ..., GL_MAP2_NORMAL);
gluNurbsSurface(nobj, ..., GL_MAP2_VERTEX_4); gluEndSurface(nobj);
See Also
gluBeginSurface, gluBeginTrim, gluNewNurbsRenderer, gluNurbsCurve,
gluPwlCurve
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ΓòÉΓòÉΓòÉ 3.163. gluOrtho2D ΓòÉΓòÉΓòÉ
OpenGL man pages
gluOrtho2D
Name
gluOrtho2D - define a 2-D orthographic projection matrix
C Specification
void gluOrtho2D( GLdouble left,
GLdouble right,
GLdouble bottom,
GLdouble top )
Parameters
left, right Specify the coordinates for the left and right vertical
clipping planes.
bottom, top Specify the coordinates for the bottom and top horizontal
clipping planes.
Description
gluOrtho2D sets up a two-dimensional orthographic viewing region. This is
equivalent to calling glOrtho with near=-1 and far=1.
See Also
glOrtho, gluPerspective
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ΓòÉΓòÉΓòÉ 3.164. gluPartialDisk ΓòÉΓòÉΓòÉ
OpenGL man pages
gluPartialDisk
Name
gluPartialDisk - draw an arc of a disk
C Specification
void gluPartialDisk( GLUquadricObj *qobj,
GLdouble innerRadius,
GLdouble outerRadius,
GLint slices,
GLint loops,
GLdouble startAngle,
GLdouble sweepAngle )
Parameters
qobj Specifies a quadrics object (created with gluNewQuadric).
innerRadius Specifies the inner radius of the partial disk (can be zero).
outerRadius Specifies the outer radius of the partial disk.
slices Specfies the number of subdivisions around the z axis.
loops Specifies the number of concentric rings about the origin into
which the partial disk is subdivided.
startAngle Specifies the starting angle, in degrees, of the disk portion.
sweepAngle Specifies the sweep angle, in degrees, of the disk portion.
Description
gluPartialDisk renders a partial disk on the z=0 plane. A partial disk is
similar to a full disk, except that only the subset of the disk from
startAngle through startAngle + sweepAngle is included (where 0 degrees is
along the +y axis, 90 degrees along the +x axis, 180 along the -y axis, and
270 along the -x axis).
The partial disk has a radius of outerRadius, and contains a concentric
circular hole with a radius of innerRadius. If innerRadius is zero, then
no hole is generated. The partial disk is subdivided around the z axis
into slices (like pizza slices), and also about the z axis into rings (as
specified by slices and loops, respectively).
With respect to orientation, the +z side of the partial disk is considered
to be outside (see gluQuadricOrientation). This means that if the
orientation is set to GLU_OUTSIDE, then any normals generated point along
the +z axis. Otherwise, they point along the -z axis.
If texturing is turned on (with gluQuadricTexture), texture coordinates are
generated linearly such that where r=outerRadius, the value at (r, 0, 0) is
(1, 0.5), at (0, r, 0) it is (0.5, 1), at (-r, 0, 0) it is (0, 0.5), and at
(0, -r, 0) it is (0.5, 0).
See Also
gluCylinder, gluDisk, gluNewQuadric, gluQuadricOrientation,
gluQuadricTexture, gluSphere
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ΓòÉΓòÉΓòÉ 3.165. gluPerspective ΓòÉΓòÉΓòÉ
OpenGL man pages
gluPerspective
Name
gluPerspective - set up a perspective projection matrix
C Specification
void gluPerspective( GLdouble fovy,
GLdouble aspect,
GLdouble zNear,
GLdouble zFar )
Parameters
fovy Specifies the field of view angle, in degrees, in the y direction.
aspect Specifies the aspect ratio that determines the field of view in the
x direction. The aspect ratio is the ratio of x (width) to y
(height).
zNear Specifies the distance from the viewer to the near clipping plane
(always positive).
zFar Specifies the distance from the viewer to the far clipping plane
(always positive).
Description
gluPerspective specifies a viewing frustum into the world coordinate
system. In general, the aspect ratio in gluPerspective should match the
aspect ratio of the associated viewport. For example, aspect=2.0 means the
viewer's angle of view is twice as wide in x as it is in y. If the viewport
is twice as wide as it is tall, it displays the image without distortion.
The matrix generated by gluPerspective is multipled by the current matrix,
just as if glMultMatrix were called with the generated matrix. To load the
perspective matrix onto the current matrix stack instead, precede the call
to gluPerspective with a call to glLoadIdentity.
Given f defined as follows:
fovy
f = cotangent(----)
2
The generated matrix is
| f |
| ------ 0 0 0 |
| aspect |
| |
| 0 f 0 0 |
| |
| zFar+zNear 2*zFar*zNear |
| 0 0 ---------- ------------ |
| zNear-zFar zNear-zFar |
| |
| 0 0 -1 0 |
Notes
Depth buffer precision is affected by the values specified for zNear and
zFar. The greater the ratio of zFar to zNear is, the less effective the
depth buffer will be at distinguishing between surfaces that are near each
other. If
zFar
r = -----
zNear
roughly log r bits of depth buffer precision are lost. Because r
2
approaches infinity as zNear approaches zero, zNear must never be set to
zero.
See Also
glFrustum, glLoadIdentity, glMultMatrix, gluOrtho2D
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ΓòÉΓòÉΓòÉ 3.166. gluPickMatrix ΓòÉΓòÉΓòÉ
OpenGL man pages
gluPickMatrix
Name
gluPickMatrix - define a picking region
C Specification
void gluPickMatrix( GLdouble x,
GLdouble y,
GLdouble width,
GLdouble height,
GLint viewport[4] )
Parameters
x, y Specify the center of a picking region in window coordinates.
width, height
Specify the width and height, respectively, of the picking region in
window coordinates.
viewport
Specifies the current viewport (as from a glGetIntegerv call).
Description
gluPickMatrix creates a projection matrix that can be used to restrict
drawing to a small region of the viewport. This is typically useful to
determine what objects are being drawn near the cursor. Use gluPickMatrix
to restrict drawing to a small region around the cursor. Then, enter
selection mode (with glRenderMode and rerender the scene. All primitives
that would have been drawn near the cursor are identified and stored in the
selection buffer.
The matrix created by gluPickMatrix is multiplied by the current matrix
just as if glMultMatrix is called with the generated matrix. To
effectively use the generated pick matrix for picking, first call
glLoadIdentity to load an identity matrix onto the perspective matrix
stack. Then call gluPickMatrix, and finally, call a command (such as
gluPerspective) to multiply the perspective matrix by the pick matrix.
When using gluPickMatrix to pick NURBS, be careful to turn off the NURBS
property GLU_AUTO_LOAD_MATRIX. If GLU_AUTO_LOAD_MATRIX is not turned off,
then any NURBS surface rendered is subdivided differently with the pick
matrix than the way it was subdivided without the pick matrix.
Example
When rendering a scene as follows:
glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(...);
glMatrixMode(GL_MODELVIEW); /* Draw the scene */
a portion of the viewport can be selected as a pick region like this:
glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPickMatrix(x, y, width,
height, viewport); gluPerspective(...); glMatrixMode(GL_MODELVIEW); /* Draw
the scene */
See Also
glGet, glLoadIndentity, glMultMatrix, glRenderMode, gluPerspective
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ΓòÉΓòÉΓòÉ 3.167. gluProject ΓòÉΓòÉΓòÉ
OpenGL man pages
gluProject
Name
gluProject - map object coordinates to window coordinates
C Specification
int gluProject( GLdouble objx,
GLdouble objy,
GLdouble objz,
const GLdouble modelMatrix[16],
const GLdouble projMatrix[16],
const GLint viewport[4],
GLdouble *winx,
GLdouble *winy,
GLdouble *winz )
Parameters
objx, objy, objz
Specify the object coordinates.
modelMatrix Specifies the current modelview matrix (as from a
glGetDoublev call).
projMatrix Specifies the current projection matrix (as from a
glGetDoublev call).
viewport Specifies the current viewport (as from a glGetIntegerv
call).
winx, winy, winz
Return the computed window coordinates.
Description
gluProject transforms the specified object coordinates into window
coordinates using modelMatrix, projMatrix, and viewport. The result is
stored in winx, winy, and winz. A return value of GL_TRUE indicates
success, and GL_FALSE indicates failure.
See Also
glGet, gluUnProject
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ΓòÉΓòÉΓòÉ 3.168. gluPwlCurve ΓòÉΓòÉΓòÉ
OpenGL man pages
gluPwlCurve
Name
gluPwlCurve - describe a piecewise linear NURBS trimming curve
C Specification
void gluPwlCurve( GLUnurbsObj *nobj,
GLint count,
GLfloat *array,
GLint stride,
GLenum type )
Parameters
nobj Specifies the NURBS object (created with gluNewNurbsRenderer).
count Specifies the number of points on the curve.
array Specifies an array containing the curve points.
stride Specifies the offset (a number of single-precision floating-point
values) between points on the curve.
type Specifies the type of curve. Must be either GLU_MAP1_TRIM_2 or
GLU_MAP1_TRIM_3.
Description
gluPwlCurve describes a piecewise linear trimming curve for a NURBS
surface. A piecewise linear curve consists of a list of coordinates of
points in the parameter space for the NURBS surface to be trimmed. These
points are connected with line segments to form a curve. If the curve is
an approximation to a real curve, the points should be close enough that
the resulting path appears curved at the resolution used in the
application.
If type is GLU_MAP1_TRIM_2, then it describes a curve in two-dimensional (u
and v) parameter space. If it is GLU_MAP1_TRIM_3, then it describes a
curve in two-dimensional homogeneous (u, v, and w) parameter space. Please
refer to the gluBeginTrim reference page for more information about
trimming curves.
Notes
To describe a trim curve which closely follows the contours of a Nurbs
surface use gluNurbsCurve.
See Also
gluBeginCurve, gluBeginTrim, gluNewNurbsRenderer, gluNurbsCurve
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ΓòÉΓòÉΓòÉ 3.169. gluQuadricCallback ΓòÉΓòÉΓòÉ
OpenGL man pages
gluQuadricCallback
Name
gluQuadricCallback - define a callback for a quadrics object
C Specification
void gluQuadricCallback( GLUquadricObj *qobj,
GLenum which,
void (*fn)( )
Parameters
qobj Specifies the quadrics object (created with gluNewQuadric).
which Specifies the callback being defined. The only valid value is
GLU_ERROR.
fn Specifies the function to be called.
Description
gluQuadricCallback is used to define a new callback to be used by a
quadrics object. If the specified callback is already defined, then it is
replaced. If fn is NULL, then any existing callback is erased.
The one legal callback is GLU_ERROR:
GLU_ERROR The function is called when an error is encountered. Its
single argument is of type GLenum, and it indicates the
specific error that occurred. Character strings describing
these errors can be retrieved with the gluErrorString call.
See Also
gluErrorString, gluNewQuadric
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ΓòÉΓòÉΓòÉ 3.170. gluQuadricDrawStyle ΓòÉΓòÉΓòÉ
OpenGL man pages
gluQuadricDrawStyle
Name
gluQuadricDrawStyle - specify the draw style desired for quadrics
C Specification
void gluQuadricDrawStyle( GLUquadricObj *qobj,
GLenum drawStyle )
Parameters
qobj Specifies the quadrics object (created with gluNewQuadric).
drawStyle Specifies the desired draw style. Valid values are GLU_FILL,
GLU_LINE, GLU_SILHOUETTE, and GLU_POINT.
Description
gluQuadricDrawStyle specifies the draw style for quadrics rendered with
qobj. The legal values are as follows:
GLU_FILL Quadrics are rendered with polygon primitives. The polygons
are drawn in a counterclockwise fashion with respect to
their normals (as defined with gluQuadricOrientation).
GLU_LINE Quadrics are rendered as a set of lines.
GLU_SILHOUETTE Quadrics are rendered as a set of lines, except that edges
separating coplanar faces will not be drawn.
GLU_POINT Quadrics are rendered as a set of points.
See Also
gluNewQuadric, gluQuadricNormals, gluQuadricOrientation, gluQuadricTexture
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ΓòÉΓòÉΓòÉ 3.171. gluQuadricNormals ΓòÉΓòÉΓòÉ
OpenGL man pages
gluQuadricNormals
Name
gluQuadricNormals - specify what kind of normals are desired for quadrics
C Specification
void gluQuadricNormals( GLUquadricObj *qobj,
GLenum normals )
Parameters
qobj Specifes the quadrics object (created with gluNewQuadric).
normals Specifies the desired type of normals. Valid values are GLU_NONE,
GLU_FLAT, and GLU_SMOOTH.
Description
gluQuadricNormals specifies what kind of normals are desired for quadrics
rendered with qobj. The legal values are as follows:
GLU_NONE No normals are generated.
GLU_FLAT One normal is generated for every facet of a quadric.
GLU_SMOOTH One normal is generated for every vertex of a quadric. This
is the default.
See Also
gluNewQuadric, gluQuadricDrawStyle, gluQuadricOrientation,
gluQuadricTexture
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ΓòÉΓòÉΓòÉ 3.172. gluQuadricOrientation ΓòÉΓòÉΓòÉ
OpenGL man pages
gluQuadricOrientation
Name
gluQuadricOrientation - specify inside/outside orientation for quadrics
C Specification
void gluQuadricOrientation( GLUquadricObj *qobj,
GLenum orientation )
Parameters
qobj Specifies the quadrics object (created with gluNewQuadric).
orientation Specifies the desired orientation. Valid values are
GLU_OUTSIDE and GLU_INSIDE.
Description
gluQuadricOrientation specifies what kind of orientation is desired for
quadrics rendered with qobj. The orientation values are as follows:
GLU_OUTSIDE Quadrics are drawn with normals pointing outward.
GLU_INSIDE Normals point inward. The default is GLU_OUTSIDE.
Note that the interpretation of outward and inward depends on the quadric
being drawn.
See Also
gluNewQuadric, gluQuadricDrawStyle, gluQuadricNormals, gluQuadricTexture
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ΓòÉΓòÉΓòÉ 3.173. gluQuadricTexture ΓòÉΓòÉΓòÉ
OpenGL man pages
gluQuadricTexture
Name
gluQuadricTexture - specify if texturing is desired for quadrics
C Specification
void gluQuadricTexture( GLUquadricObj *qobj,
GLboolean textureCoords )
Parameters
qobj Specifies the quadrics object (created with gluNewQuadric).
textureCoords Specifies a flag indicating if texture coordinates should be
generated.
Description
gluQuadricTexture specifies if texture coordinates should be generated for
quadrics rendered with qobj. If the value of textureCoords is GL_TRUE,
then texture coordinates are generated, and if textureCoords is GL_FALSE,
they are not. The default is GL_FALSE.
The manner in which texture coordinates are generated depends upon the
specific quadric rendered.
See Also
gluNewQuadric, gluQuadricDrawStyle, gluQuadricNormals,
gluQuadricOrientation
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ΓòÉΓòÉΓòÉ 3.174. gluScaleImage ΓòÉΓòÉΓòÉ
OpenGL man pages
gluScaleImage
Name
gluScaleImage - scale an image to an arbitrary size
C Specification
int gluScaleImage( GLenum format,
GLint widthin,
GLint heightin,
GLenum typein,
const void *datain,
GLint widthout,
GLint heightout,
GLenum typeout,
void *dataout )
Parameters
format Specifies the format of the pixel data. The following symbolic
values are valid: GL_COLOR_INDEX, GL_STENCIL_INDEX,
GL_DEPTH_COMPONENT, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB,
GL_RGBA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
widthin, heightin
Specify the width and height, respectively, of the source image
that is scaled.
typein Specifies the data type for datain. Must be one of
GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,
GL_SHORT, GL_UNSIGNED_INT, GL_INT, or GL_FLOAT.
datain Specifies a pointer to the source image.
widthout, heightout
Specify the width and height, respectively, of the destination
image.
typeout Specifies the data type for dataout. Must be one of
GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,
GL_SHORT, GL_UNSIGNED_INT, GL_INT, or GL_FLOAT.
dataout Specifies a pointer to the destination image.
Description
gluScaleImage scales a pixel image using the appropriate pixel store modes
to unpack data from the source image and pack data into the destination
image.
When shrinking an image, gluScaleImage uses a box filter to sample the
source image and create pixels for the destination image. When magnifying
an image, the pixels from the source image are linearly interpolated to
create the destination image.
A return value of zero indicates success, otherwise a GLU error code is
returned indicating what the problem was (see gluErrorString).
Please refer to the glReadPixels reference page for a description of the
acceptable values for the format, typein, and typeout parameters.
See Also
glDrawPixels, glReadPixels, gluBuild1DMipmaps, gluBuild2DMipmaps,
gluErrorString
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ΓòÉΓòÉΓòÉ 3.175. gluSphere ΓòÉΓòÉΓòÉ
OpenGL man pages
gluSphere
Name
gluSphere - draw a sphere
C Specification
void gluSphere( GLUquadricObj *qobj,
GLdouble radius,
GLint slices,
GLint stacks )
Parameters
qobj Specifies the quadrics object (created with gluNewQuadric).
radius Specifies the radius of the sphere.
slices Specifies the number of subdivisions around the z axis (similar to
lines of longitude).
stacks Specifies the number of subdivisions along the z axis (similar to
lines of latitude).
Description
gluSphere draws a sphere of the given radius centered around the origin.
The sphere is subdivided around the z axis into slices and along the z axis
into stacks (similar to lines of longitude and latitude).
If the orientation is set to GLU_OUTSIDE (with gluQuadricOrientation), then
any normals generated point away from the center of the sphere. Otherwise,
they point toward the center of the sphere.
If texturing is turned on (with gluQuadricTexture), then texture
coordinates are generated so that t ranges from 0.0 at z=-radius to 1.0 at
z=radius (t increases linearly along longitudinal lines), and s ranges from
0.0 at the +y axis, to 0.25 at the +x axis, to 0.5 at the -y axis, to 0.75
at the -x axis, and back to 1.0 at the +y axis.
See Also
gluCylinder, gluDisk, gluNewQuadric, gluPartialDisk, gluQuadricOrientation
gluQuadricTexture
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ΓòÉΓòÉΓòÉ 3.176. gluTessBeginContour ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessBeginContour (GLU version 1.2 and later)
Name
gluTessBeginContour, gluTessEndContour - delimit a contour description
C Specification
void gluTessBeginContour( GLUtesselator *tess )
void gluTessEndContour( GLUtesselator *tess )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
Description
gluTessBeginContour and gluTessEndContour delimit the definition of a
polygon contour. Within each gluTessBeginContour/gluTessEndContour pair,
there can be zero or more calls to gluTessVertex. The vertices specify a
closed contour (the last vertex of each contour is automatically linked to
the first). See the gluTessVertex reference page for more details.
gluTessBeginContour can only be called between gluTessBeginPolygon and
gluTessEndPolygon.
See Also
gluNewTess, gluTessBeginPolygon, gluTessVertex, gluTessCallback,
gluTessProperty, gluTessNormal, gluTessEndPolygon
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ΓòÉΓòÉΓòÉ 3.177. gluTessBeginPolygon ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessBeginPolygon (GLU version 1.2 and later)
Name
gluTessBeginPolygon - delimit a polygon description
C Specification
void gluTessBeginPolygon( GLUtesselator *tess,
void *polygon_data )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
polygon_data Specifies a pointer to user polygon data.
Description
gluTessBeginPolygon and gluTessEndPolygon delimit the definition of a
nonconvex polygon. Within each gluTessBeginPolygon/gluTessEndPolygon pair,
there must be one or more calls to gluTessBeginContour/gluTessEndContour.
Within each contour, there are zero or more calls to gluTessVertex. The
vertices specify a closed contour (the last vertex of each contour is
automatically linked to the first). See the gluTessVertex,
gluTessBeginContour and gluTessEndContour reference pages for more details.
polygon_data is a pointer to a user-defined data structure. If the
appropriate callback(s) are specified (see gluTessCallback), then this
pointer is returned to the callback function(s). Thus, it is a convenient
way to store per-polygon information.
Once gluTessEndPolygon is called, the polygon is tessellated, and the
resulting triangles are described through callbacks. See gluTessCallback
for descriptions of the callback functions.
Example
A quadrilateral with a triangular hole in it can be described like this:
gluTessBeginPolygon(tobj, NULL);
gluTessBeginContour(tobj);
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluTessEndContour(tobj);
gluTessBeginContour(tobj);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluTessEndContour(tobj);
gluTessEndPolygon(tobj);
See Also
gluNewTess, gluTessBeginContour, gluTessVertex, gluTessCallback,
gluTessProperty, gluTessNormal gluTessEndPolygon
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ΓòÉΓòÉΓòÉ 3.178. gluTessCallback ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessCallback (GLU version 1.2 and later)
Name
gluTessCallback - define a callback for a tessellation object
C Specification
void gluTessCallback( GLUtesselator *tess,
GLenum which,
void (*fn)() )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
which Specifies the callback being defined. The following values are
valid: GLU_TESS_BEGIN, GLU_TESS_BEGIN_DATA, GLU_TESS_EDGE_FLAG,
GLU_TESS_EDGE_FLAG_DATA, GLU_TESS_VERTEX, GLU_TESS_VERTEX_DATA,
GLU_TESS_END, GLU_TESS_END_DATA, GLU_TESS_COMBINE,
GLU_TESS_COMBINE_DATA, GLU_TESS_ERROR, and GLU_TESS_ERROR_DATA.
fn Specifies the function to be called.
Description
gluTessCallback is used to indicate a callback to be used by a tessellation
object. If the specified callback is already defined, then it is replaced.
If fn is NULL, then the existing callback becomes undefined.
These callbacks are used by the tessellation object to describe how a
polygon specified by the user is broken into triangles. Note that there are
two versions of each callback: one with user-specified polygon data and one
without. If both versions of a particular callback are specified then the
callback with user-specified polygon data will be used. Note that
"polygon_data" is a copy of the pointer that was specified when
gluTessBeginPolygon was called.
The legal callbacks are as follows:
GLU_TESS_BEGIN
The begin callback is invoked like glBegin to indicate the start
of a (triangle) primitive. The function takes a single argument
of type GLenum. If the GLU_TESS_BOUNDARY_ONLY property is set to
GL_FALSE then the argument is set to either GL_TRIANGLE_FAN,
GL_TRIANGLE_STRIP, or GL_TRIANGLES. If the GLU_TESS_BOUNDARY_ONLY
property is set to GL_TRUE then the argument will be set to
GL_LINE_LOOP. The function prototype for this callback looks
like:
void begin ( GLenum type );
GLU_TESS_BEGIN_DATA
The same as the GLU_TESS_BEGIN callback except that it takes an
additional pointer argument. This pointer is identical to the
opaque pointer provided when gluTessBeginPolygon was called. The
function prototype for this callback looks like:
void beginData ( GLenum type, void *polygon_data );
GLU_TESS_EDGE_FLAG
The edge flag callback is similar to glEdgeFlag. The function
takes a single Boolean flag that indicates which edges lie on the
polygon boundary. If the flag is GL_TRUE, then each vertex that
follows begins an edge which lies on the polygon boundary -- that
is, an edge which separates an interior region from an exterior
one. If the flag is GL_FALSE, then each vertex that follows
begins an edge which lies in the polygon interior. The edge flag
callback (if defined) is invoked before the first vertex callback
is made.
Since triangle fans and triangle strips do not support edge
flags, the begin callback is not called with GL_TRIANGLE_FAN or
GL_TRIANGLE_STRIP if an edge flag callback is provided. Instead,
the fans and strips are converted to independent triangles. The
function prototype for this callback looks like:
void edgeFlag ( GLboolean flag );
GLU_TESS_EDGE_FLAG_DATA
The same as the GLU_TESS_EDGE_FLAG callback except that it takes
an additional pointer argument. This pointer is identical to the
opaque pointer provided when gluTessBeginPolygon was called. The
function prototype for this callback looks like:
void edgeFlagData ( GLboolean flag, void *polygon_data );
GLU_TESS_VERTEX
The vertex callback is invoked between the begin and end
callbacks. It is similar to glVertex, and it defines the
vertices of the triangles created by the tessellation process.
The function takes a pointer as its only argument. This pointer
is identical to the opaque pointer provided by the user when the
vertex was described (see gluTessVertex). The function prototype
for this callback looks like:
void vertex ( void *vertex_data );
GLU_TESS_VERTEX_DATA
The same as the GLU_TESS_VERTEX callback except that it takes an
additional pointer argument. This pointer is identical to the
opaque pointer provided when gluTessBeginPolygon was called. The
function prototype for this callback looks like:
void vertexData ( void *vertex_data, void *polygon_data );
GLU_TESS_END
The end callback serves the same purpose as glEnd. It indicates
the end of a primitive and it takes no arguments. The function
prototype for this callback looks like:
void end ( void );
GLU_TESS_END_DATA
The same as the GLU_TESS_END callback except that it takes an
additional pointer argument. This pointer is identical to the
opaque pointer provided when gluTessBeginPolygon was called. The
function prototype for this callback looks like:
void endData ( void *polygon_data);
GLU_TESS_COMBINE
The combine callback is called to create a new vertex when the
tessellation detects an intersection, or wishes to merge
features. The function takes four arguments: an array of three
elements each of type GLdouble, an array of four pointers, an
array of four elements each of type GLfloat, and a pointer to a
pointer. The prototype looks like:
void combine( GLdouble coords[3], void *vertex_data[4],
GLfloat weight[4], void **outData );
The vertex is defined as a linear combination of up to 4 existing
vertices, stored in vertex_data. The coefficients of the linear
combination are given by weight; these weights always sum to 1.0.
All vertex pointers are valid even when some of the weights are
zero. coords gives the location of the new vertex.
The user must allocate another vertex, interpolate parameters
using vertex_data and weight, and return the new vertex pointer
in outData. This handle is supplied during rendering callbacks.
The user is responsible for freeing the memory sometime after
gluTessEndPolygon is called.
For example, if the polygon lies in an arbitrary plane in 3-space,
and we associate a color with each vertex, the GLU_TESS_COMBINE
callback might look like this:
void myCombine( GLdouble coords[3], VERTEX *d[4],
GLfloat w[4], VERTEX **dataOut )
{
VERTEX *new = new_vertex();
new->x = coords[0];
new->y = coords[1];
new->z = coords[2];
new->r = w[0]*d[0]->r + w[1]*d[1]->r + w[2]*d[2]->r + w[3]*d[3]->r;
new->g = w[0]*d[0]->g + w[1]*d[1]->g + w[2]*d[2]->g + w[3]*d[3]->g;
new->b = w[0]*d[0]->b + w[1]*d[1]->b + w[2]*d[2]->b + w[3]*d[3]->b;
new->a = w[0]*d[0]->a + w[1]*d[1]->a + w[2]*d[2]->a + w[3]*d[3]->a;
*dataOut = new;
}
If the tessellation detects an intersection, then the
GLU_TESS_COMBINE or GLU_TESS_COMBINE_DATA callback (see below)
must be defined, and it must write a non-NULL pointer into
dataOut. Otherwise the GLU_TESS_NEED_COMBINE_CALLBACK error
occurs, and no output is generated. (This is the only error that
can occur during tessellation and rendering.)
GLU_TESS_COMBINE_DATA
The same as the GLU_TESS_COMBINE callback except that it takes an
additional pointer argument. This pointer is identical to the
opaque pointer provided when gluTessBeginPolygon was called. The
function prototype for this callback looks like:
void combineData ( GLdouble coords[3], void *vertex_data[4],
GLfloat weight[4], void **outData,
void *polygon_data );
GLU_TESS_ERROR
The error callback is called when an error is encountered. The
one argument is of type GLenum; it indicates the specific error
that occurred and will be set to one of
GLU_TESS_MISSING_BEGIN_POLYGON, GLU_TESS_MISSING_END_POLYGON,
GLU_TESS_MISSING_BEGIN_CONTOUR, GLU_TESS_MISSING_END_CONTOUR,
GLU_TESS_COORD_TOO_LARGE, GLU_TESS_NEED_COMBINE_CALLBACK.
Character strings describing these errors can be retrieved with
the gluErrorString call. The function prototype for this callback
looks like:
void error ( GLenum errno );
The GLU library will recover from the first four errors by
inserting the missing call(s). GLU_TESS_COORD_TOO_LARGE says
that some vertex coordinate exceeded the predefined constant
GLU_TESS_MAX_COORD in absolute value, and that the value has been
clamped. (Coordinate values must be small enough so that two can
be multiplied together without overflow.)
GLU_TESS_NEED_COMBINE_CALLBACK says that the tessellation
detected an intersection between two edges in the input data, and
the GLU_TESS_COMBINE or GLU_TESS_COMBINE_DATA callback was not
provided. No output will be generated.
GLU_TESS_ERROR_DATA
The same as the GLU_TESS_ERROR callback except that it takes an
additional pointer argument. This pointer is identical to the
opaque pointer provided when gluTessBeginPolygon was called. The
function prototype for this callback looks like:
void errorData ( GLenum errno, void *polygon_data );
Example
Polygons tessellated can be rendered directly like this:
gluTessCallback(tobj, GLU_TESS_BEGIN, glBegin);
gluTessCallback(tobj, GLU_TESS_VERTEX, glVertex3dv);
gluTessCallback(tobj, GLU_TESS_END, glEnd);
gluTessCallback(tobj, GLU_TESS_COMBINE, myCombine);
gluTessBeginPolygon(tobj, NULL);
gluTessBeginContour(tobj);
gluTessVertex(tobj, v, v);
...
gluTessEndContour(tobj);
gluTessEndPolygon(tobj);
Typically, the tessellated polygon should be stored in a display list so
that it does not need to be retessellated every time it is rendered.
See Also
glBegin, glEdgeFlag, glVertex, gluNewTess, gluErrorString, gluTessVertex,
gluTessBeginPolygon, gluTessBeginContour, gluTessProperty, gluTessNormal
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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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ΓòÉΓòÉΓòÉ 3.179. gluTessCallback ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessCallback (GLU versions 1.0 and 1.1)
Name
gluTessCallback - define a callback for a tessellation object
C Specification
void gluTessCallback( GLUtriangulatorObj *tobj,
GLenum which,
void (*fn)( )
Parameters
tobj Specifies the tessellation object (created with gluNewTess).
which Specifies the callback being defined. The following values are
valid: GLU_BEGIN, GLU_EDGE_FLAG, GLU_VERTEX, GLU_END, and GLU_ERROR.
fn Specifies the function to be called.
Description
gluTessCallback is used to indicate a callback to be used by a tessellation
object. If the specified callback is already defined, then it is replaced.
If fn is NULL, then the existing callback is erased.
These callbacks are used by the tessellation object to describe how a
polygon specified by the user is broken into triangles.
The legal callbacks are as follows:
GLU_BEGIN The begin callback is invoked like glBegin to indicate the start
of a (triangle) primitive. The function takes a single argument
of type GLenum that is either GL_TRIANGLE_FAN, GL_TRIANGLE_STRIP,
or GL_TRIANGLES.
GLU_EDGE_FLAG
The edge flag callback is similar to glEdgeFlag. The function
takes a single Boolean flag that indicates which edges of the
created triangles were part of the original polygon defined by
the user, and which were created by the tessellation process. If
the flag is GL_TRUE, then each vertex that follows begins an edge
that was part of the original polygon. If the flag is GL_FALSE,
then each vertex that follows begins an edge that was generated
by the tessellator. The edge flag callback (if defined) is
invoked before the first vertex callback is made.
Since triangle fans and triangle strips do not support edge
flags, the begin callback is not called with GL_TRIANGLE_FAN or
GL_TRIANGLE_STRIP if an edge flag callback is provided. Instead,
the fans and strips are converted to independent triangles.
GLU_VERTEX
The vertex callback is invoked between the begin and end
callbacks. It is similar to glVertex, and it defines the
vertices of the triangles created by the tessellation process.
The function takes a pointer as its only argument. This pointer
is identical to the opaque pointer provided by the user when the
vertex was described (see gluTessVertex).
GLU_END The end callback serves the same purpose as glEnd. It indicates
the end of a primitive and it takes no arguments.
GLU_ERROR The error callback is called when an error is encountered. The
one argument is of type GLenum, and it indicates the specific
error that occurred. There are eight errors unique to polygon
tessellation, named GLU_TESS_ERROR1 through GLU_TESS_ERROR8.
Character strings describing these errors can be retrieved with
the gluErrorString call.
Example
Polygons tessellated can be rendered directly like this:
gluTessCallback(tobj, GLU_BEGIN, glBegin);
gluTessCallback(tobj, GLU_VERTEX, glVertex3dv);
gluTessCallback(tobj, GLU_END, glEnd);
gluBeginPolygon(tobj);
gluTessVertex(tobj, v, v);
...
gluEndPolygon(tobj);
Typically, the tessellated polygon should be stored in a display list so
that it does not need to be retessellated every time it is rendered.
See Also
glBegin, glEdgeFlag, glVertex, gluDeleteTess, gluErrorString, gluNewTess,
gluTessVertex
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.180. gluTessEndPolygon ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessEndPolygon (GLU version 1.2 and later)
Name
gluTessEndPolygon - delimit a polygon description
C Specification
void gluTessEndPolygon( GLUtesselator *tess )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
Description
gluTessBeginPolygon and gluTessEndPolygon delimit the definition of a
nonconvex polygon. Within each gluTessBeginPolygon/gluTessEndPolygon pair,
there must be one or more calls to gluTessBeginContour/gluTessEndContour.
Within each contour, there are zero or more calls to gluTessVertex. The
vertices specify a closed contour (the last vertex of each contour is
automatically linked to the first). See the gluTessVertex,
gluTessBeginContour and gluTessEndContour reference pages for more details.
Once gluTessEndPolygon is called, the polygon is tessellated, and the
resulting triangles are described through callbacks. See gluTessCallback
for descriptions of the callback functions.
Example
A quadrilateral with a triangular hole in it can be described like this:
gluTessBeginPolygon(tobj, NULL);
gluTessBeginContour(tobj);
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluTessEndContour(tobj);
gluTessBeginContour(tobj);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluTessEndContour(tobj);
gluTessEndPolygon(tobj);
See Also
gluNewTess, gluTessBeginContour, gluTessVertex, gluTessCallback,
gluTessProperty, gluTessNormal, gluTessBeginPolygon
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.181. gluTessNormal ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessNormal (GLU version 1.2 and later)
Name
gluTessNormal - specify a normal for a polygon
C Specification
void gluTessNormal( GLUtesselator *tess,
GLdouble x,
GLdouble y,
GLdouble z )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
x Specifies the first component of the normal.
y Specifies the second component of the normal.
z Specifies the third component of the normal.
Description
gluTessNormal describes a normal for a polygon that the user is defining.
All input data will be projected onto a plane perpendicular to one of the
three coordinate axes before tessellation and all output triangles will be
oriented CCW with respect to the normal (CW orientation can be obtained by
reversing the sign of the supplied normal). For example, if you know that
all polygons lie in the x-y plane, call gluTessNormal(tess, 0.0, 0.0, 1.0)
before rendering any polygons.
If the supplied normal is (0,0,0) (the default value), the normal is
determined as follows. The direction of the normal, up to its sign, is
found by fitting a plane to the vertices, without regard to how the
vertices are connected. It is expected that the input data lies
approximately in the plane; otherwise projection perpendicular to one of
the three coordinate axes may substantially change the geometry. The sign
of the normal is chosen so that the sum of the signed areas of all input
contours is non-negative (where a CCW contour has positive area).
The supplied normal persists until it is changed by another call to
gluTessNormal.
See Also
gluTessBeginPolygon, gluTessEndPolygon
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.182. gluTessProperty ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessProperty (GLU version 1.2 and later)
Name
gluTessProperty - set a tessellation object property
C Specification
void gluTessProperty( GLUtesselator *tess,
GLenum which,
GLdouble value )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
which Specifies the property to be set. Valid values are
GLU_TESS_WINDING_RULE, GLU_TESS_BOUNDARY_ONLY, GLU_TESS_TOLERANCE.
value Specifies the value of the indicated property.
Description
gluTessProperty is used to control properties stored in a tessellation
object. These properties affect the way that the polygons are interpreted
and rendered. The legal values for which are as follows:
GLU_TESS_WINDING_RULE determines which parts of the polygon are on the
"interior". value may be set to one of
GLU_TESS_WINDING_ODD, GLU_TESS_WINDING_NONZERO,
GLU_TESS_WINDING_POSITIVE, or
GLU_TESS_WINDING_NEGATIVE, or
GLU_TESS_WINDING_ABS_GEQ_TWO.
To understand how the winding rule works first
consider that the input contours partition the
plane into regions. The winding rule determines
which of these regions are inside the polygon.
For a single contour C, the winding number of a
point x is simply the signed number of revolutions
we make around x as we travel once around C (where
CCW is positive). When there are several contours,
the individual winding numbers are summed. This
procedure associates a signed integer value with
each point x in the plane. Note that the winding
number is the same for all points in a single
region.
The winding rule classifies a region as "inside"
if its winding number belongs to the chosen
category (odd, nonzero, positive, negative, or
absolute value of at least two). The previous GLU
tessellator (prior to GLU 1.2) used the "odd"
rule. The "nonzero" rule is another common way to
define the interior. The other three rules are
useful for polygon CSG operations.
GLU_TESS_BOUNDARY_ONLY is a boolean value ("value" should be set to
GL_TRUE or GL_FALSE). When set to GL_TRUE, a set
of closed contours separating the polygon interior
and exterior are returned instead of a
tessellation. Exterior contours are oriented CCW
with respect to the normal, interior contours are
oriented CW. The GLU_TESS_BEGIN and
GLU_TESS_BEGIN_DATA callbacks use the type
GL_LINE_LOOP for each contour.
GLU_TESS_TOLERANCE specifies a tolerance for merging features to
reduce the size of the output. For example, two
vertices which are very close to each other might
be replaced by a single vertex. The tolerance is
multiplied by the largest coordinate magnitude of
any input vertex; this specifies the maximum
distance that any feature can move as the result
of a single merge operation. If a single feature
takes part in several merge operations, the total
distance moved could be larger.
Feature merging is completely optional; the
tolerance is only a hint. The implementation is
free to merge in some cases and not in others, or
to never merge features at all. The default
tolerance is zero.
The current implementation merges vertices only if
they are exactly coincident, regardless of the
current tolerance. A vertex is spliced into an
edge only if the implementation is unable to
distinguish which side of the edge the vertex lies
on. Two edges are merged only when both endpoints
are identical.
See Also
gluGetTessProperty
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.183. gluTessVertex ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessVertex (GLU version 1.2 and later)
Name
gluTessVertex - specify a vertex on a polygon
C Specification
void gluTessVertex( GLUtesselator *tess,
GLdouble coords[3],
void *data )
Parameters
tess Specifies the tessellation object (created with gluNewTess).
coords Specifies the location of the vertex.
data Specifies an opaque pointer passed back to the user with the vertex
callback (as specified by gluTessCallback).
Description
gluTessVertex describes a vertex on a polygon that the user is defining.
Successive gluTessVertex calls describe a closed contour. For example, if
the user wants to describe a quadrilateral, then gluTessVertex should be
called four times. gluTessVertex can only be called between
gluTessBeginContour and gluTessEndContour.
data normally points to a structure containing the vertex location, as well
as other per-vertex attributes such as color and normal. This pointer is
passed back to the user through the GLU_TESS_VERTEX or GLU_TESS_VERTEX_DATA
callback after tessellation (see the gluTessCallback reference page).
Example
A quadrilateral with a triangular hole in it can be described as follows:
gluTessBeginPolygon(tobj, NULL);
gluTessBeginContour(tobj);
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluTessEndContour(tobj);
gluTessBeginContour(tobj);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluTessEndContour(tobj); gluTessEndPolygon(tobj);
See Also
gluTessBeginPolygon, gluNewTess, gluTessBeginContour, gluTessCallback,
gluTessProperty, gluTessNormal, gluTessEndPolygon
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 3.184. gluTessVertex ΓòÉΓòÉΓòÉ
OpenGL man pages
gluTessVertex (GLU versions 1.0 and 1.1)
Name
gluTessVertex - specify a vertex on a polygon
C Specification
void gluTessVertex( GLUtriangulatorObj *tobj,
GLdouble v[3],
void *data )
Parameters
tobj Specifies the tessellation object (created with gluNewTess).
v Specifies the location of the vertex.
data Specifies an opaque pointer passed back to the user with the vertex
callback (as specified by gluTessCallback).
Description
gluTessVertex describes a vertex on a polygon that the user is defining.
Successive gluTessVertex calls describe a closed contour. For example, if
the user wants to describe a quadrilateral, then gluTessVertex should be
called four times. gluTessVertex can only be called between
gluBeginPolygon and gluEndPolygon.
data normally points to a structure containing the vertex location, as well
as other per-vertex attributes such as color and normal. This pointer is
passed back to the user through the GLU_VERTEX callback after tessellation
(see the gluTessCallback reference page).
Example
A quadrilateral with a triangular hole in it can be described as follows:
gluBeginPolygon(tobj);
gluTessVertex(tobj, v1, v1);
gluTessVertex(tobj, v2, v2);
gluTessVertex(tobj, v3, v3);
gluTessVertex(tobj, v4, v4);
gluNextContour(tobj, GLU_INTERIOR);
gluTessVertex(tobj, v5, v5);
gluTessVertex(tobj, v6, v6);
gluTessVertex(tobj, v7, v7);
gluEndPolygon(tobj);
See Also
gluBeginPolygon, gluNewTess, gluNextContour, gluTessCallback
ΓòÉΓòÉΓòÉ 3.185. gluUnProject ΓòÉΓòÉΓòÉ
OpenGL man pages
gluUnProject
Name
gluUnProject - map window coordinates to object coordinates
C Specification
int gluUnProject( GLdouble winx,
GLdouble winy,
GLdouble winz,
const GLdouble modelMatrix[16],
const GLdouble projMatrix[16],
const GLint viewport[4],
GLdouble *objx,
GLdouble *objy,
GLdouble *objz )
Parameters
winx, winy, winz
Specify the window coordinates to be mapped.
modelMatrix Specifies the modelview matrix (as from a glGetDoublev
call).
projMatrix Specifies the projection matrix (as from a glGetDoublev
call).
viewport Specifies the viewport (as from a glGetIntegerv call).
objx, objy, objz
Returns the computed object coordinates.
Description
gluUnProject maps the specified window coordinates into object coordinates
using modelMatrix, projMatrix, and viewport. The result is stored in objx,
objy, and objz. A return value of GL_TRUE indicates success, and GL_FALSE
indicates failure.
See Also
glGet, gluProject
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
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ΓòÉΓòÉΓòÉ 4. OpenGL Index of routines in Specification Order ΓòÉΓòÉΓòÉ
OpenGL man pages
Table of Contents
Chapter 1. Fundamentals
Chapter 2. Rasterization
Chapter 3. Per-Fragment Operations and the Framebuffer
Chapter 4. Special Functions
Chapter 5. State and State Requests
OpenGL on the X Window System(tm)
The OpenGL Utility Library
The Vertex Array Extension
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Chapter 1. Fundamentals
glGetError
glGetError
glBegin
glBegin, glEnd
glVertex
glVertex2d, glVertex2dv, glVertex2f, glVertex2fv, glVertex2i,
glVertex2iv, glVertex2s, glVertex2sv, glVertex3d, glVertex3dv,
glVertex3f, glVertex3fv, glVertex3i, glVertex3iv, glVertex3s,
glVertex3sv, glVertex4d, glVertex4dv, glVertex4f, glVertex4fv,
glVertex4i, glVertex4iv, glVertex4s, glVertex4sv
glNormal
glNormal3b, glNormal3bv, glNormal3d, glNormal3dv, glNormal3f,
glNormal3fv, glNormal3i, glNormal3iv, glNormal3s, glNormal3sv
glColor
glColor3b, glColor3bv, glColor3d, glColor3dv, glColor3f,
glColor3fv, glColor3i, glColor3iv, glColor3s, glColor3sv,
glColor3ub, glColor3ubv, glColor3ui, glColor3uiv, glColor3us,
glColor3usv, glColor4b, glColor4bv, glColor4d, glColor4dv,
glColor4f, glColor4fv, glColor4i, glColor4iv, glColor4s, glColor4sv,
glColor4ub, glColor4ubv, glColor4ui, glColor4uiv, glColor4us,
glColor4usv
glIndex
glIndexd, glIndexdv, glIndexf, glIndexfv, glIndexi, glIndexiv,
glIndexs, glIndexsv
glTexCoord
glTexCoord1d, glTexCoord1dv, glTexCoord1f, glTexCoord1fv,
glTexCoord1i, glTexCoord1iv, glTexCoord1s, glTexCoord1sv,
glTexCoord2d, glTexCoord2dv, glTexCoord2f, glTexCoord2fv,
glTexCoord2i, glTexCoord2iv, glTexCoord2s, glTexCoord2sv,
glTexCoord3d, glTexCoord3dv, glTexCoord3f, glTexCoord3fv,
glTexCoord3i, glTexCoord3iv, glTexCoord3s, glTexCoord3sv,
glTexCoord4d, glTexCoord4dv, glTexCoord4f, glTexCoord4fv,
glTexCoord4i, glTexCoord4iv, glTexCoord4s, glTexCoord4sv
glEdgeFlag
glEdgeFlag, glEdgeFlagv
glRect
glRectd, glRectdv, glRectf, glRectfv, glRecti, glRectiv, glRects,
glRectsv
glViewport
glViewport
glDepthRange
glDepthRange
glMatrixMode
glMatrixMode
glLoadMatrix
glLoadMatrixd, glLoadMatrixf
glMultMatrix
glMultMatrixd, glMultMatrixf
glLoadIdentity
glLoadIdentity
glRotate
glRotated, glRotatef
glTranslate
glTranslated, glTranslatef
glScale
glScaled, glScalef
glFrustum
glFrustum
glOrtho
glOrtho
glPushMatrix
glPushMatrix, glPopMatrix
glEnable
glEnable, glDisable
glTexGen
glTexGend, glTexGendv, glTexGenf, glTexGenfv, glTexGeni, glTexGeniv
glClipPlane
glClipPlane
glRasterPos
glRasterPos2d, glRasterPos2dv, glRasterPos2f, glRasterPos2fv,
glRasterPos2i, glRasterPos2iv, glRasterPos2s, glRasterPos2sv,
glRasterPos3d, glRasterPos3dv, glRasterPos3f, glRasterPos3fv,
glRasterPos3i, glRasterPos3iv, glRasterPos3s, glRasterPos3sv,
glRasterPos4d, glRasterPos4dv, glRasterPos4f, glRasterPos4fv,
glRasterPos4i, glRasterPos4iv, glRasterPos4s, glRasterPos4sv
glFrontFace
glFrontFace
glMaterial
glMaterialf, glMaterialfv, glMateriali, glMaterialiv
glLight
glLightf, glLightfv, glLighti, glLightiv
glLightModel
glLightModelf, glLightModelfv, glLightModeli, glLightModeliv
glColorMaterial
glColorMaterial
glShadeModel
glShadeModel
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Chapter 2. Rasterization
glPointSize
glPointSize
glLineWidth
glLineWidth
glLineStipple
glLineStipple
glCullFace
glCullFace
glPolygonStipple
glPolygonStipple
glPolygonMode
glPolygonMode
glPixelStore
glPixelStoref, glPixelStorei
glPixelTransfer
glPixelTransferf, glPixelTransferi
glPixelMap
glPixelMapfv, glPixelMapuiv, glPixelMapusv
glDrawPixels
glDrawPixels
glPixelZoom
glPixelZoom
glBitmap
glBitmap
glTexImage2D
glTexImage2D
glTexImage1D
glTexImage1D
glTexParameter
glTexParameterf, glTexParameterfv, glTexParameteri, glTexParameteriv
glTexEnv
glTexEnvf, glTexEnvfv, glTexEnvi, glTexEnviv
glFog
glFogf, glFogfv, glFogi, glFogiv
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Chapter 3. Per-Fragment Operations and the Framebuffer
glScissor
glScissor
glAlphaFunc
glAlphaFunc
glStencilFunc
glStencilFunc
glStencilOp
glStencilOp
glDepthFunc
glDepthFunc
glBlendFunc
glBlendFunc
glLogicOp
glLogicOp
glDrawBuffer
glDrawBuffer
glIndexMask
glIndexMask
glColorMask
glColorMask
glDepthMask
glDepthMask
glStencilMask
glStencilMask
glClear
glClear
glClearColor
glClearColor
glClearIndex
glClearIndex
glClearDepth
glClearDepth
glClearStencil
glClearStencil
glClearAccum
glClearAccum
glAccum
glAccum
glReadPixels
glReadPixels
glReadBuffer
glReadBuffer
glCopyPixels
glCopyPixels
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Chapter 4. Special Functions
glMap1
glMap1d, glMap1f
glMap2
glMap2d, glMap2f
glEvalCoord
glEvalCoord1d, glEvalCoord1dv, glEvalCoord1f, glEvalCoord1fv,
glEvalCoord2d, glEvalCoord2dv, glEvalCoord2f, glEvalCoord2fv
glMapGrid
glMapGrid1d, glMapGrid1f, glMapGrid2d, glMapGrid2f
glEvalMesh
glEvalMesh1, glEvalMesh2
glEvalPoint
glEvalPoint1, glEvalPoint2
glInitNames
glInitNames
glPushName
glPushName, glPopName
glLoadName
glLoadName
glRenderMode
glRenderMode
glSelectBuffer
glSelectBuffer
glFeedbackBuffer
glFeedbackBuffer
glPassThrough
glPassThrough
glNewList
glNewList, glEndList
glCallList
glCallList
glCallLists
glCallLists
glListBase
glListBase
glGenLists
glGenLists
glIsList
glIsList
glDeleteLists
glDeleteLists
glFlush
glFlush
glFinish
glFinish
glHint
glHint
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Chapter 5. State and State Requests
glGet
glGetBooleanv, glGetDoublev, glGetFloatv, glGetIntegerv
glIsEnabled
glIsEnabled
glGetClipPlane
glGetClipPlane
glGetLight
glGetLightfv, glGetLightiv
glGetMaterial
glGetMaterialfv, glGetMaterialiv
glGetTexEnv
glGetTexEnvfv, glGetTexEnviv
glGetTexGen
glGetTexGendv, glGetTexGenfv, glGetTexGeniv
glGetTexParameter
glGetTexParameterfv, glGetTexParameteriv
glGetTexLevelParameter
glGetTexLevelParameterfv, glGetTexLevelParameteriv
glGetPixelMap
glGetPixelMapfv, glGetPixelMapuiv, glGetPixelMapusv
glGetMap
glGetMapdv, glGetMapfv, glGetMapiv
glGetTexImage
glGetTexImage
glGetPolygonStipple
glGetPolygonStipple
glGetString
glGetString
glPushAttrib
glPushAttrib, glPopAttrib
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OpenGL on the X Window System(tm)
glXIntro
Introduction
glXQueryExtension
glXQueryExtension
glXQueryVersion
glXQueryVersion
glXGetConfig
glXGetConfig
glXChooseVisual
glXChooseVisual
glXCreateGLXPixmap
glXCreateGLXPixmap
glXDestroyGLXPixmap
glXDestroyGLXPixmap
glXCreateContext
glXCreateContext
glXIsDirect
glXIsDirect
glXDestroyContext
glXDestroyContext
glXCopyContext
glXCopyContext
glXMakeCurrent
glXMakeCurrent
glXGetCurrentContext
glXGetCurrentContext
glXGetCurrentDrawable
glXGetCurrentDrawable
glXWaitGL
glXWaitGL
glXWaitX
glXWaitX
glXSwapBuffers
glXSwapBuffers
glXUseXFont
glXUseXFont
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
The OpenGL Utility Library
See notes on the new GLU tesselator
gluScaleImage
gluScaleImage
gluBuild1DMipmaps
gluBuild1DMipmaps
gluBuild2DMipmaps
gluBuild2DMipmaps
gluOrtho2D
gluOrtho2D
gluPerspective
gluPerspective
gluLookAt
gluLookAt
gluPickMatrix
gluPickMatrix
gluProject
gluProject
gluUnProject
gluUnProject
gluNewQuadric
gluNewQuadric
gluDeleteQuadric
gluDeleteQuadric
gluQuadricCallback
gluQuadricCallback
gluQuadricNormals
gluQuadricNormals
gluQuadricTexture
gluQuadricTexture
gluQuadricOrientation
gluQuadricOrientation
gluQuadricDrawStyle
gluQuadricDrawStyle
gluSphere
gluSphere
gluCylinder
gluCylinder
gluDisk
gluDisk
gluPartialDisk
gluPartialDisk
gluNewNurbsRenderer
gluNewNurbsRenderer
gluDeleteNurbsRenderer
gluDeleteNurbsRenderer
gluNurbsCallback
gluNurbsCallback
gluBeginCurve
gluBeginCurve, gluEndCurve
gluNurbsCurve
gluNurbsCurve
gluBeginSurface
gluBeginSurface, gluEndSurface
gluNurbsSurface
gluNurbsSurface
gluBeginTrim
gluBeginTrim, gluEndTrim
gluPwlCurve
gluPwlCurve
gluNurbsProperty
gluNurbsProperty
gluLoadSamplingMatrices
gluLoadSamplingMatrices
gluGetNurbsProperty
gluGetNurbsProperty
gluErrorString
gluErrorString
The GLU tesselator for GLU versions 1.0 and 1.1:
gluNewTess
gluNewTess
gluDeleteTess
gluDeleteTess
gluTessCallback
gluTessCallback
gluBeginPolygon
gluBeginPolygon, gluEndPolygon
gluTessVertex
gluTessVertex
gluNextContour
gluNextContour
The GLU tesselator for GLU version 1.2 and later:
gluNewTess
gluNewTess
gluDeleteTess
gluDeleteTess
gluTessCallback
gluTessCallback
gluTessBeginPolygon
gluTessBeginPolygon
gluTessEndPolygon
gluTessEndPolygon
gluTessVertex
gluTessVertex
gluTessBeginContour
gluBeginContour, gluEndContour
gluTessProperty
gluTessProperty
gluGetTessProperty
gluGetTessProperty
gluTessNormal
gluTessNormal
gluBeginPolygon
gluBeginPolygon, gluEndPolygon (Obsolete)
gluNextContour
gluNextContour (Obsolete)
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
The Vertex Array Extension
glArrayElementEXT
glArrayElementEXT
glColorPointerEXT
glColorPointerEXT
glDrawArraysEXT
glDrawArraysEXT
glEdgeFlagPointerEXT
glEdgeFlagPointerEXT
glGetPointervEXT
glGetPointervEXT
glIndexPointerEXT
glIndexPointerEXT
glNormalPointerEXT
glNormalPointerEXT
glTexCoordPointerEXT
glTexCoordPointerEXT
glVertexPointerEXT
glVertexPointerEXT
ΓòÉΓòÉΓòÉ 5. GLU Version 1.2 Polygon Tessellator Notes ΓòÉΓòÉΓòÉ
OpenGL man pages
Some notes on the new polygon tessellator in GLU version 1.2
GLU version 1.2 introduces a new polygon tessellator. The following routines
have become obsolete and should not be used for new development based on GLU
version 1.2 and later.
Obsolete Routine Replace with
gluBeginPolygon gluTessBeginPolygon; gluTessBeginContour
gluEndPolygon gluTessEndContour; gluTessEndPolygon
gluNextContour gluTessEndContour; gluTessBeginContour
The following routines are new in GLU version 1.2:
gluGetTessProperty
gluTessBeginContour
gluTessBeginPolygon
gluTessEndContour
gluTessEndPolygon
gluTessNormal
gluTessProperty
Some routines have had an argument or return-value changed from
``GLUtriangulatorObj *'' to ``GLUtesselator *''. Since the GLU header file for
version 1.2 has a typedef from GLUtriangulatorObj to GLUtesselator, source code
should not need any immediate changes. However, at some time the source code
should be moved to the GLU version 1.2 name.
gluBeginPolygon
gluDeleteTess
gluEndPolygon
gluNewTess
gluNextContour
gluTessCallback
gluTessVertex
One routine has been expanded to support more valid values for the which
argument:
gluTessCallback
To distinguish what version of the GLU library you are using at compile time,
check for the following pre-processor symbols:
none defined version 1.0
GLU_VERSION_1_1 version 1.1 or later
GLU_VERSION_1_2 version 1.2 or later
Digital Open3D supports the following versions of the GLU library:
Digital Open3D Version GLU Version Supported
Before Version 2.6 version 1.0
Version 2.6 version 1.1
Version 3.0 and later version 1.2
ΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇΓöÇ
Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
Look here for legal stuff: Legal
ΓòÉΓòÉΓòÉ 6. OpenGL on X-Windows ΓòÉΓòÉΓòÉ
OpenGL man pages
glXIntro
Name
glXIntro - Introduction to OpenGL in the X window system
OVERVIEW
OpenGL is a high-performance 3-D-oriented renderer. It is available in the
X window system through the GLX extension. Use glXQueryExtension and
glXQueryVersion to establish whether the GLX extension is supported by an X
server, and if so, what version is supported.
GLX extended servers make a subset of their visuals available for OpenGL
rendering. Drawables created with these visuals can also be rendered using
the core X renderer and with the renderer of any other X extension that is
compatible with all core X visuals.
GLX extends drawables with several buffers other than the standard color
buffer. These buffers include back and auxiliary color buffers, a depth
buffer, a stencil buffer, and a color accumulation buffer. Some or all are
included in each X visual that supports OpenGL.
To render using OpenGL into an X drawable, you must first choose a visual
that defines the required OpenGL buffers. glXChooseVisual can be used to
simplify selecting a compatible visual. If more control of the selection
process is required, use XGetVisualInfo and glXGetConfig to select among
all the available visuals.
Use the selected visual to create both a GLX context and an X drawable.
GLX contexts are created with glXCreateContext, and drawables are created
with either XCreateWindow or glXCreateGLXPixmap. Finally, bind the context
and the drawable together using glXMakeCurrent. This context/drawable pair
becomes the current context and current drawable, and it is used by all
OpenGL commands until glXMakeCurrent is called with different arguments.
Both core X and OpenGL commands can be used to operate on the current
drawable. The X and OpenGL command streams are not synchronized, however,
except at explicitly created boundaries generated by calling glXWaitGL,
glXWaitX, XSync, and glFlush.
Examples
Below is the minimum code required to create an RGBA-format, OpenGL-
compatible X window and clear it to yellow. The code is correct, but it
does not include any error checking. Return values dpy, vi, cx, cmap, and
win should all be tested.
#include <GL/glx.h> #include <GL/gl.h> #include <unistd.h>
static int attributeList[] = { GLX_RGBA, None };
static Bool WaitForNotify(Display *d, XEvent *e, char *arg) {
return (e->type == MapNotify) && (e->xmap.window == (Window)arg); }
int main(int argc, char **argv) {
Display *dpy;
XVisualInfo *vi;
Colormap cmap;
XSetWindowAttributes swa;
Window win;
GLXContext cx;
XEvent event;
/* get a connection */
dpy = XOpenDisplay(0);
/* get an appropriate visual */
vi = glXChooseVisual(dpy, DefaultScreen(dpy), attributeList);
/* create a GLX context */
cx = glXCreateContext(dpy, vi, 0, GL_TRUE);
/* create a color map */
cmap = XCreateColormap(dpy, RootWindow(dpy, vi->screen),
vi->visual, AllocNone);
/* create a window */
swa.colormap = cmap;
swa.border_pixel = 0;
swa.event_mask = StructureNotifyMask;
win = XCreateWindow(dpy, RootWindow(dpy, vi->screen), 0, 0, 100, 100,
0, vi->depth, InputOutput, vi->visual,
CWBorderPixel|CWColormap|CWEventMask, &swa);
XMapWindow(dpy, win);
XIfEvent(dpy, &event, WaitForNotify, (char*)win);
/* connect the context to the window */
glXMakeCurrent(dpy, win, cx);
/* clear the buffer */
glClearColor(1,1,0,1);
glClear(GL_COLOR_BUFFER_BIT);
glFlush();
/* wait a while */
sleep(10); }
Notes
A color map must be created and passed to XCreateWindow. See the example
code above.
A GLX context must be created and attached to an X drawable before OpenGL
commands can be executed. OpenGL commands issued while no context/drawable
pair is current are ignored.
Exposure events indicate that all buffers associated with the specified
window may be damaged and should be repainted. Although certain buffers of
some visuals on some systems may never require repainting (the depth
buffer, for example), it is incorrect to code assuming that these buffers
will not be damaged.
GLX commands manipulate XVisualInfo structures rather than pointers to
visuals or visual IDs. XVisualInfo structures contain visual, visualID,
screen, and depth elements, as well as other X-specific information.
See Also
glFinish, glFlush, glXChooseVisual, glXCopyContext, glXCreateContext,
glXCreateGLXPixmap, glXDestroyContext, glXGetConfig, glXIsDirect,
glXMakeCurrent, glXQueryExtension, glXQueryVersion, glXSwapBuffers,
glXUseXFont, glXWaitGL, glXWaitX, XCreateColormap, XCreateWindow, XSync
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Introduction | Alphabetic | Specification
Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
Look here for legal stuff: Legal
ΓòÉΓòÉΓòÉ 7. External links ΓòÉΓòÉΓòÉ
This chapter contains all URLs referenced in this book. Each page from this
chapter contain a link which will launch IBM Web Explorer on a specific URL.
ΓòÉΓòÉΓòÉ 7.1. http://www.digital.com/ ΓòÉΓòÉΓòÉ
The link you selected points to Digital Corp. WWW site.
Click the URL below to launch IBM Web Explorer
http://www.digital.com/
ΓòÉΓòÉΓòÉ 7.2. http://www.digital.com/info/tm.html ΓòÉΓòÉΓòÉ
The link you selected points to Digital Corp. WWW site, legal info page.
Click the URL below to launch IBM Web Explorer
http://www.digital.com/info/tm.html
ΓòÉΓòÉΓòÉ 7.3. http://www.sgi.com/Technology/openGL/ ΓòÉΓòÉΓòÉ
This link points to OpenGL homepage on the Silicon Graphics web site.
Click the URL below to launch IBM Web Explorer
http://www.sgi.com/Technology/openGL/
ΓòÉΓòÉΓòÉ 7.4. http://www.sgi.com/Technology/openGL/glspec1.1/glspec.html ΓòÉΓòÉΓòÉ
This link points to the header page of OpenGL 1.1 specification
located in the Silicon Graphics web site.
Click the URL below to launch IBM Web Explorer
http://www.sgi.com/Technology/openGL/glspec1.1/glspec.html
ΓòÉΓòÉΓòÉ 7.5. mailto:andy.vesper@eng.pko.dec.com ΓòÉΓòÉΓòÉ
This page contains the Andy Vesper`s e-mail address
Click the URL below to launch IBM Web Explorer
mailto:andy.vesper@eng.pko.dec.com
mailto:andy.vesper@pko.mts.dec.com